What is "real" RPM and is it at all meaningful

[Ice Man]

[This is an amazing description of this stat/stats in general.

Yes, it is.

Spaceman, you should start up a Chicago Bulls statistics thread and moderate the proceedings. You not only know your stuff, but you know how to communicate it too.

[musiqsoulchild]

The list of this stat on ESPN's NBA page has Butler as the best Bulls player at 41st which should make this a total B.S. stat.

Mirotic is the second listed Bull at 64th and Rose clocks in at 145th.

WTF?

So I'll say this:

Stats in the (+/-) family are not meant to be taken as "player x is better than player y". At the heart, these statistics are meant to measure "when player x steps on the court, his team improves by x amount". This is an absolutely crucial distinction to make, because so often people look at stats like this and say "No way are Manu Ginobili and Amir Johnson better than Kevin Durant, this is B.S." So this isn't a stat you can just look at and stop thinking, in fact these stats are designed to inform your thinking. People who get really into plus minus stats (like myself) do so because the numbers that are spit out match pretty much exactly what we see on film.

So what is this measuring? Basically, the idea is that every player in the NBA plays in a multitude of lineups every season and that using all of this lineup data, you can measure the precise impact of each individual player on the scoring margin.. Think of it like an algebra problem, where

scoring margin= Bulls1+Bulls2+Bulls3+Bulls4+Bulls5-Jazz1-Jazz2-Jazz3-Jazz4-Jazz5

If you do this over thousands of lineups and thousands of opponent lineups, you can start to get a good picture of each of the individual variables in this equation. (Note here that Bulls 1,2,3 would be Jordan, Pippen, Rodman, etc.)

RPM is the latest version of this type of stat, which uses box score data to make the results look more "intuitive". I wholeheartedly disagree with this approach, but since this is the most easily available plus minus stat complaining doesn't do a whole lot of good.

The important thing to remember is that you should take these number for exactly what they are: a given player's impact on the scoring margin. Nothing more, nothing less.So for example, I still think Durant is a better player than Ginobili, because his skill set is superior, he plays the #1 role on offense, and he plays far more minutes than Ginobili. I sort of "filter" RAPM data through my own observations to come up with a clear picture of a given player. So the data are telling me that Ginobili, in his role, is one of the most impactful players in the league. But when you consider how limited his role actually is, I'm not likely to rank him very highly overall.

Regarding your questions about specific Bulls players, all I'm going to say is that years and years of data agree that players who play the way Rose has this season do not help their teams win. And players like Mirotic who shoot well and space the floor are far more impactful than you'd think (look at nba.com's lineup data, Mirotic is a part of basically all of the Bulls' best offensive lineups).

You are putting in serious work in this thread!

[dice]

iceman wrote

Fair enough. I won't argue that. What I take away from that stat is those guys might be more useful than most of us think. Hell, Green beat our ass once this year, Whiteside did in another game, and Nene did during last year's playoffs. Plus we know how Korver can be. So yes while I am not saying they are better than Butler, I can see how they affect games. Morris ... hmmm ... I gotta think more about that

.

It's one thing to say that you can see how they affect games which I can't argue with.

But do you actually accept that their respective rankings - 12th, 14th, 18th, 25th and 32nd in the entire NBA - are valid?

if you're looking for a more reasonable player ranking by RPM, sort by WAR (wins above replacement), which estimates how many of a team's wins a particular player is theoretically responsible for. weeds out guys who haven't played as much

[JerrySloan]

Depends what you mean by valid. When these guys have been on the court, their teams have done unusually well. That is a valid statement. However, nobody would pick Kyle Korver 12th in a league-wide draft, in forming actual teams trying to win actual game. Nor any of those other guys according to their placements.

What that tells me is that some of their high placement is situational, and would not be repeated on other teams at other times. Some is luck. Some is the guy playing over his head. And some, perhaps, is that the player is underrated, and the RAPM statistic captures the underrating effect.

Invalid? I dunno. It's a stat. Steve Kerr has the highest winning percentage of any active NBA coach. That is a valid statistic. If I try to make too much it, though, then I start talking nonsense. Which is what I would be doing if I took RAPM as God's answer and pounded the table that Kyle Korver is the 12th best player in the NBA.

I think you misunderstood my question.

I meant do you believe that Korver, e.g., really has had much more positive impact on the court for Atlanta than Butler has had for the Bulls?

[Ice Man]

do you believe that Korver, e.g., really has had much more positive impact on the court for Atlanta than Butler has had for the Bulls?

Probably not. On the other hand, Atlanta has won a lot more games than Chicago, so it's not unreasonable to think that somebody on Atlanta has been better than Butler.

Let's just say that I could maybe believe that Korver has had a stronger impact per minute, which is how RAPM operates. Maybe. I certainly would not believe that is true if taking into account Jimmy's extra minutes and evaluating at the game level.

[Keller61]

But do you actually accept that their respective rankings - 12th, 14th, 18th, 25th and 32nd in the entire NBA - are valid?

Depends what you mean by valid. When these guys have been on the court, their teams have done unusually well. That is a valid statement. However, nobody would pick Kyle Korver 12th in a league-wide draft, in forming actual teams trying to win actual game. Nor any of those other guys according to their placements.

What that tells me is that some of their high placement is situational, and would not be repeated on other teams at other times. Some is luck. Some is the guy playing over his head. And some, perhaps, is that the player is underrated, and the RAPM statistic captures the underrating effect.

Invalid? I dunno. It's a stat. Steve Kerr has the highest winning percentage of any active NBA coach. That is a valid statistic. If I try to make too much it, though, then I start talking nonsense. Which is what I would be doing if I took RAPM as God's answer and pounded the table that Kyle Korver is the 12th best player in the NBA.

I definitely think luck has something to do with it. I take stats like these with a big grain of salt because they try to assign a constant value to the other players on the court. In reality, the performance of NBA players can vary greatly from game to game, month to month, and season to season. Bad players are really good on some nights, good players are really bad on others, guys go through hot stretches and cold stretches, etc. Some players change dramatically over the course of a season (consider Tony Snell earlier this year vs. now). I don't think you can just assume that that all averages out.

I'm guessing that Butler's relatively low ranking has something to do with guys like Noah, Taj, and Kirk performing worse this season than the stat expects them to. There's no way Butler is a negative impact player on defense, but it might look that way this year if you assume he is playing with the 2013-14 versions of those other guys.

That doesn't even get into the role of system and coaching, which is probably most relevant in the case of Atlanta. Is Kyle Korver really a much better player this year than he has been throughout his career, or is he just being utilized much more effectively? I think the reason you see some "role players" with really good RAPM is because their coaches know how to use them in a role which helps the team. It doesn't mean that their value would translate to any situation. With superstars like Durant, you don't need to look at numbers to recognize the value they would bring to any team.

[Ice Man]

I'm guessing that Butler's relatively low ranking has something to do with guys like Noah, Taj, and Kirk performing worse this season than the stat expects them to. There's no way Butler is a negative impact player on defense, but it might look that way this year if you assume he is playing with the 2013-14 versions of those other guy

That seems like a good hypothesis, if that version of the stat used last year's prior's.

The good of these RAPM statistics is that they take into consideration many things. As is the bad. Interpreting the output can be a bitch.

[Ice Man]

Is Kyle Korver really a much better player this year than he has been throughout his career, or is he just being utilized much more effectively?

That's also a good point. It may be that Thibs isn't a guru for 3 point shooters. Korver's efficiency declined when he joined the Bulls and rose when he left. Marco did better when he left. Mike's efficiency is down a bit (although he is getting older, that is part of it too). Meanwhile, Bud seems to be quite the offensive coach.

As I wrote, there are a lot of factors that need unpacking. And if we're not talking out of our tails, but are actually doing meaningful analysis, each of these factors need their own studies.

[Dr Spaceman]

Yes, it is.

Spaceman, you should start up a Chicago Bulls statistics thread and moderate the proceedings. You not only know your stuff, but you know how to communicate it too.

If it's something this board would be interested in, I'd be more than happy to do that. I think I'd prefer to call it the "analytics" thread, because what I'm interested in is the interpretation and usage, not just the stats themselves. But yeah, I think it's a good idea and I'd be happy to take that on if it's something people want.

You are putting in serious work in this thread!

Thank you, much appreciated!

This is an amazing description of this stat/stats in general. I love the way you describe why Ginobili rats out higher than Durant.

Good work.

Are you studying/do you have a job doing something statistics related?

Thanks. Not formally educated in statistics, but I've taken a few classes. Really I'm kind of self-taught, I spend a lot of time analyzing basketball and soaked up my knowledge from hanging around the true statisticians .The thing that separates me from them is that I've been told I have a pretty excellent gift for digesting complicated subjects and explaining them in ways that other people can grasp. So that's really all I'm doing here.

I actually study psychology/chemistry in school. About 3/4ths of the way through undergrad, and I'll go on to medical school after I graduate.

[dice]

Yes, it is.

Spaceman, you should start up a Chicago Bulls statistics thread and moderate the proceedings. You not only know your stuff, but you know how to communicate it too.

If it's something this board would be interested in, I'd be more than happy to do that. I think I'd prefer to call it the "analytics" thread, because what I'm interested in is the interpretation and usage, not just the stats themselves. But yeah, I think it's a good idea and I'd be happy to take that on if it's something people want.

if you do, don't let it interfere with your schoolwork!

there is, after all, a separate forum for this kind of stuff. not bulls-centric, but still

[Dr Spaceman]

I meant do you believe that Korver, e.g., really has had much more positive impact on the court for Atlanta than Butler has had for the Bulls?

There's a reason I have a picture of Korver as my avatar

You may not realize it, but this is one of the most important questions you could've asked in your quest to understand impact statistics. This is generally the part of the conversation where people tend to look at me sideways or even outright dismiss me, so I really hope you'll read this with an open mind.

Think about this: on offense, a basketball player is always in one of two conditions. Either he has the ball, or he doesn't. A player can contribute by doing good things with the ball (this is what's captured by the box score and what most people focus on when watching games) or he can do good things without the ball (this is something that isn't traditionally measured by any of our counting statistics and something most people don''t notice).

Now with that in mind, consider Korver's shooting. Obviously, people see that he scores 12 ppg and question how this guy can be seriously considered an impact player. But consider a couple things: among players who have equalled Korver's 3 point shooting volume in history, the highest percentage ever recorded was 45%. Korver is currently shooting 49.6%. He's bombing 3s at a rate equivalent to some of the highest in history, and he's hitting them at a percentage no one has ever come close to. On Catch & Shoot plays, per NBA.com, Korver is averaging over 1.3 points per possession. The best offense in NBA history scored about 1.15 points per possession.

Now another thing Korver has mastered is being a brutally quick decision maker. He catches and either shoots if he's open or finds an open teammate to pass to. This means that failed attempts to get him the ball cost very little shot clock time, and he's not taking bad shots when he does possess the ball. This is the most underrated aspect of what made guys like Bird and Jordan so ridiculous on offense. It was always catch, read, attack or pass within the blink of an eye. Korea does this as well as anyone, and the result is he doesn't waste possessions. His teammates who are better at isolating and pick and roll have more shot clock to work with.

And another thing in Korver's favor: right now he leads the league in True Shooting Percentage. What that means in practice is that a shot attempt by Korver on average results in more points than a shot attempt by any other player in the NBA. This is a big, big deal.

Okay so we've established what Korver does with the ball that makes him so special, but what about without the ball? Well, given that he's the best in the league when he actually does decide to shoot, any reasonable opposing coach is going to do their best to keep the ball out of his hands. And this is the secret to the Hawks offensive success. It's almost a joke how far opposing teams will go to stop Korver from shooting. I'm talking doubles at the 3 point line, switching every screen, I've even seen multiple times this year opposing defenses concede an open dunk just to avoid Korver being open. It's ridiculous.

And Korver does not behave like a normal shooter. Watch him during a Hawks game sometime, he's constantly moving, sprinting in circles around the arc, making decisive dives to the corner. He's the biggest threat on the Hawks, and all eyes are on him all the time. Defenses literally treat him like he's LeBron.

We imagine the typical low volume 3 point shooter as a guy who sits in the corner and shoots when he's passed to. But this is not the case with Kyle. The Hawks will run him around screen after screen, watch the defense shatter, and then attack the craters he leaves behind. They are so brutally effective at using Korver's gravity to set up 2-on-1s and mismatch isolations. Korea doesn't get credited with an assist on these plays, but he deserves it.

And think about what you'd do if you're defending a pick-and-roll with Korver lurking on the weak side. You absolutely cannot help off of him. In Thibodeau's defensive scheme, the weak side corner help man needs to drop into the paint and bump the roll man, impeding his way to the basket. But if that defender is guarding Korver, you can't use that guy to help on the pick and roll at all. Watch the Hawks run pick and roll, and it honestly looks like you could drive a semi through the lane at times.

So yeah, Korver is having tangible, transcendent impact every single possession, and he never even has to touch the ball to do so.

So big picture, what does this mean? I don't think Korver is a better basketball player than Jimmy Butler. Butler has much better defensive told, a more versatile skill set, and can be a high-usage guy in a way that Korver can't. However, Jimmy Butler is not having as much impact on the basketball court as Korver is right now. Very few players are.

And this gets a little philosophical, but follow me here: we tend to think of basketball players in terms of how well they could do without quality talent around them. But to me this is a fallacy, because if the goal is to win a championship, I want players that play really well when they have other talented players around them, even if they need other talent to do their thing effectively.

A real world example: The Knicks would be far, far worse with Korver in place of Carmelo. This is a given, since Carmelo is much better suited to carrying a team like that. But flip things around: do you honestly believe the Hawks would be better with Carmelo in place of Korver? Because I legitimately don't. I think the Hawks would be worse with Carmelo.

Another real-world example: You have the option of putting any shooting guard in the league on the Cavaliers. do you pick anyone other than Korver? The guy is going to make life so much easier for the other offensive stars, and when he does use possessions, he's going to use them better than even the other stars would!

Now what you'll take issue with is Korver's context-dependency. And that's totally fair, and for a lot of teams they wouldn't hesitate to take a litany of other guys over Korver. But think about this: is it more valuable to make a bad team mediocre, or to be able to make a great team championship-worthy? Because the latter is what Korver does. And I'll take that over the Carmelo's of the world any day.

Wow that was long. Anyway this is why I'm such a huge advocate of film study. Once you accept RAPM as being a valid indicator of "impact" you start looking at basketball in a different way, and start to understand the unseen impact of guys like Korver. Other big ones are Steve Nash, Bill Walton, David Robinson, etc.

[Chicago-Bull-E]

^ Very cool post. Really good insight, can't say I disagree with any of it.

[dice]

xRAPM ("real RAPM") quarter century team:

1st team:

PG jason kidd
W lebron james
W kobe bryant
B tim duncan (passing shaq for overall MVP this season)
B shaquille o'neal

2nd team:

PG john stockton
W paul pierce
W dwyane wade
B kevin garnett
B david robinson

3rd team:

PG chris paul
W scottie pippen
W andrei kirilenko
B dirk nowitzki
B car malone

it's a shame that play-by-play data doesn't go back further. this is really the only kind of data that could be used to fairly compare across the eras

[musiqsoulchild]

xRAPM ("real RAPM") quarter century team:

1st team:

PG jason kidd
W lebron james
W kobe bryant
B tim duncan (passing shaq for overall MVP this season)
B shaquille o'neal

2nd team:

PG john stockton
W paul pierce
W dwyane wade
B kevin garnett
B david robinson

3rd team:

PG chris paul
W scottie pippen
W andrei kirilenko
B dirk nowitzki
B car malone

it's a shame that play-by-play data doesn't go back further. this is really the only kind of data that could be used to fairly compare across the eras

Only player that you argue with would be Kirilenko. Otherwise thats an outstanding 15.

I may quibble about Chris Paul a little, but its not egregious.

[Keller61]

Wow that was long. Anyway this is why I'm such a huge advocate of film study. Once you accept RAPM as being a valid indicator of "impact" you start looking at basketball in a different way, and start to understand the unseen impact of guys like Korver. Other big ones are Steve Nash, Bill Walton, David Robinson, etc.

I'm perfectly willing to acknowledge and discuss the unseen impact of certain players, but I prefer to do so using my eyes and not RAPM. I think there is too much noise in the data and too many uncontrollable variables for it to be a reliable measurement.

Let me challenge you with another example: DJ Augustin had one of the worst RAPM's in the league last season (-4.88). Most of us who watched thought he had a tremendous positive impact on the Bulls and was one of the key reasons for how the season turned around. Did we all get suckered, or did RAPM just whiff on that one?

[dice]

Wow that was long. Anyway this is why I'm such a huge advocate of film study. Once you accept RAPM as being a valid indicator of "impact" you start looking at basketball in a different way, and start to understand the unseen impact of guys like Korver. Other big ones are Steve Nash, Bill Walton, David Robinson, etc.

I'm perfectly willing to acknowledge and discuss the unseen impact of certain players, but I prefer to do so using my eyes and not RAPM. I think there is too much noise in the data and too many uncontrollable variables for it to be a reliable measurement.

Let me challenge you with another example: DJ Augustin had one of the worst RAPM's in the league last season (-4.88). Most of us who watched thought he had a tremendous positive impact on the Bulls and was one of the key reasons for how the season turned around. Did we all get suckered, or did RAPM just whiff on that one?

3/4 season data is a pretty small sample size. also, the comparison of what he provided offensively to the rest of that team probably made him look better than he actually was. i'd say the offensive portion of the RAPM shortchanged him a bit, but i'm not gonna dispute his bad defensive rating

[Dr Spaceman]

Wow that was long. Anyway this is why I'm such a huge advocate of film study. Once you accept RAPM as being a valid indicator of "impact" you start looking at basketball in a different way, and start to understand the unseen impact of guys like Korver. Other big ones are Steve Nash, Bill Walton, David Robinson, etc.

I'm perfectly willing to acknowledge and discuss the unseen impact of certain players, but I prefer to do so using my eyes and not RAPM. I think there is too much noise in the data and too many uncontrollable variables for it to be a reliable measurement.

Let me challenge you with another example: DJ Augustin had one of the worst RAPM's in the league last season (-4.88). Most of us who watched thought he had a tremendous positive impact on the Bulls and was one of the key reasons for how the season turned around. Did we all get suckered, or did RAPM just whiff on that one?

I'm not sure where you're getting that data from, but I see Augustin as -3.25. Regardless, your point still stands.

Augustin has a -0.29 offense split and a -3.00 defense split. So basically his offense is neutral to slight negative and his defense is dreadful. Do you disagree with this characterization?

Remember that this is not rating "DJ's Augustin's value over Kirk Hinrich". It's DJ Augustin's relative performance of his role. Basically he's a slightly below average offensive starting point guard and a very poor defender. Again, do you disagree with this characterization?

I'm not saying it's perfect, and indeed if he made a quantum jump last year the regression is going to trend him toward zero rather than assign him a level of play that he's extraordinarily unlikely to maintain over more than a handful of games. And indeed he's been awful everywhere outside of a couple month stretch in Chicago. Remember, RAPM is interested in predicting team wins, so betting on a player like Augustin to continue his play for any length of time is unwise.