How were Jokic and Luka able to break the advanced defensive rating codes?

[dygaction]

Obviously not many people think they are great defenders, but on BBRef, Jokic is #1 in DBPM and Luka is #3. The other top 5 are Caruso, Embiid, Butler, Simmons, Giannis; in Defensive Win Shares, Luka is #2, with Mobley #1, followed by Embiid, Jarrett Allen, Giannis, Zubac, Tatum...
Luka was #8 in 2022 nba player defensive ratings (https://www.statmuse.com/nba/ask/2023-nba-players-defensive-rating-rankings) and is now #11 among all and the highest among guards (https://www.statmuse.com/nba/ask/2023-nba-players-defensive-rating-rankings).
Question, what factors were evaluated with too much weight to lead to these results, what are the more reliable defensive stats, or are their defense not as bad as they were portraited to be?

[Doctor MJ]

I won't address every stat here. Here are the key points to me:

1. The box score doesn't include all basketball value, and this is particularly a problem on defense.

2. When a team supports an offensive star by having a defensive orientation around him when he plays, and staggers other offensive players when he's resting, +/- based stats will have a tendency to overrate the star's defense and underrate his offense.

Note that this doesn't even necessarily mean "put all the good defenders out there with him". Teammates might just understand that when they are out there with the offensive star, their job is to focus more on defense and let him take care of the creation.

3. All of these stats are about what happens in the average regular season game. They don't speak to how resilient he is to tactical adjustments in a playoff series. How effective a defender a player is when he's not being targeted is only part of the equation.

As I say all of this, and while I don't consider either of these guys All-D defenders, I should also say that I don't refuse to consider them as All-D type guys simply because they have clear weaknesses. A player's total value is always based on his strengths as well as his weaknesses, and we're talking about two really, really smart BBIQ guys. Hence, it will always remain a possibility, in my approach, that these guys do find a way to become star defensive payers in their impact despite the weaknesses...

but they are going to need to show it to me in the playoffs, repeatedly, before I'm likely to be sold.

[LukaTheGOAT]

Using solely the box-score to evaluate defense is very risky, and I would advise heavily against it.

If you look at stuff that incorporates plus-minus, then I think you get a better picture of where they are at. For example, if we take a look at their ranks in some hybrid metrics that include the box-score and plus-minus (to see how the team does with them on versus off the court)

ESPN D-RPM
Jokic-34th
Doncic-83rd

Defensive Estimated Plus-Minus
Jokic-73rd
Doncic-149th

*Note does not include today's games.

You could also look at RAPM which is pure plus-minus (although not sure I love it for only single year purposes) and

NBA Shot Charts D-RAPM
Jokic-120th
Doncic-414th

Now, Doncic and Jokic look MUCH closer to the middle of the pack. And this is not even considering the fact that defense in the postseason is a whole different ball game than the RS, and you could argue their value as defenders' changes depending on matchups.

[Dutchball97]

Both Jokic and Luka are high up the rankings for defensive rebounds and steals but iirc assists also improve DBPM for reason. I like BPM as an overall stat at least as far as boxscore metrics go but DBPM shouldn't really ever be used on it's own.

[OhayoKD]

Both Jokic and Luka are high up the rankings for defensive rebounds and steals but iirc assists also improve DBPM for reason. I like BPM as an overall stat at least as far as boxscore metrics go but DBPM shouldn't really ever be used on it's own.

Shouldn't dbpm just not be used

[Dutchball97]

Both Jokic and Luka are high up the rankings for defensive rebounds and steals but iirc assists also improve DBPM for reason. I like BPM as an overall stat at least as far as boxscore metrics go but DBPM shouldn't really ever be used on it's own.

Shouldn't dbpm just not be used

What I meant was don't use DBPM as a stat in itself but I'm not someone who disregards BPM as a whole because of it. I've seen people only use OBPM for offense but I value BPM as a catch all stat too as long as you're aware it's not the best at measuring defensive impact. Although I think it goes for every single stat that you need to take the formula into account like what it overvalues or undervalues compared to other stats. Every stat has value but no stat is gospel kind of thing.

[OhayoKD]

Both Jokic and Luka are high up the rankings for defensive rebounds and steals but iirc assists also improve DBPM for reason. I like BPM as an overall stat at least as far as boxscore metrics go but DBPM shouldn't really ever be used on it's own.

Shouldn't dbpm just not be used

What I meant was don't use DBPM as a stat in itself but I'm not someone who disregards BPM as a whole because of it. I've seen people only use OBPM for offense but I value BPM as a catch all stat too as long as you're aware it's not the best at measuring defensive impact. Although I think it goes for every single stat that you need to take the formula into account like what it overvalues or undervalues compared to other stats. Every stat has value but no stat is gospel kind of thing.

Could you explain what you think the value of using dbpm is instead of just keeping the obpm and chucking the rest? Like couldn't you just look at steals/blocks/rebounds if you wanted that granular context?

[Dutchball97]

Shouldn't dbpm just not be used

What I meant was don't use DBPM as a stat in itself but I'm not someone who disregards BPM as a whole because of it. I've seen people only use OBPM for offense but I value BPM as a catch all stat too as long as you're aware it's not the best at measuring defensive impact. Although I think it goes for every single stat that you need to take the formula into account like what it overvalues or undervalues compared to other stats. Every stat has value but no stat is gospel kind of thing.

Could you explain what you think the value of using dbpm is instead of just keeping the obpm and chucking the rest? Like couldn't you just look at steals/blocks/rebounds if you wanted that granular context?

It's a tough one and I can't give a definite answer to this to be honest. OBPM and DBPM aren't calculated seperately. BPM gets calculated as a whole and then they try to single out how much of that comes from the offensive side and whatever value is left gets dumped on DBPM, at least that's roughly how it works. It's just a bit messy and I'm not sure if it means OBPM is inherently more trustworthy than BPM itself.

I do like to incorporate as many stats as possible in my evaluations but for modern times I don't weigh BPM all that heavily compared to stuff like EPM and LEBRON. For the 74-96 period it's one of the best stats we have though.

[OhayoKD]

What I meant was don't use DBPM as a stat in itself but I'm not someone who disregards BPM as a whole because of it. I've seen people only use OBPM for offense but I value BPM as a catch all stat too as long as you're aware it's not the best at measuring defensive impact. Although I think it goes for every single stat that you need to take the formula into account like what it overvalues or undervalues compared to other stats. Every stat has value but no stat is gospel kind of thing.

Could you explain what you think the value of using dbpm is instead of just keeping the obpm and chucking the rest? Like couldn't you just look at steals/blocks/rebounds if you wanted that granular context?

It's a tough one and I can't give a definite answer to this to be honest. OBPM and DBPM aren't calculated seperately. BPM gets calculated as a whole and then they try to single out how much of that comes from the offensive side and whatever value is left gets dumped on DBPM, at least that's roughly how it works. It's just a bit messy and I'm not sure if it means OBPM is inherently more trustworthy than BPM itself.

Do you know how they separate offense from defense?

I do like to incorporate as many stats as possible in my evaluations but for modern times I don't weigh BPM all that heavily compared to stuff like EPM and LEBRON. For the 74-96 period it's one of the best stats we have though.

Ehhhhh, I'd be careful using it as a historical player evaluator. It's basically a pure box thing like PER/ws/48 pre-97 and even the years right after would be affected by the priors. Additionally, since we dont even have all the stats for historical players from the 70's, older players get underrated

[CharityStripe34]

Luka and Jokic have secret RealGM accounts and study stats before games to maximize lineups for their stats.

[Dutchball97]

Could you explain what you think the value of using dbpm is instead of just keeping the obpm and chucking the rest? Like couldn't you just look at steals/blocks/rebounds if you wanted that granular context?

It's a tough one and I can't give a definite answer to this to be honest. OBPM and DBPM aren't calculated seperately. BPM gets calculated as a whole and then they try to single out how much of that comes from the offensive side and whatever value is left gets dumped on DBPM, at least that's roughly how it works. It's just a bit messy and I'm not sure if it means OBPM is inherently more trustworthy than BPM itself.

Do you know how they separate offense from defense?

I do like to incorporate as many stats as possible in my evaluations but for modern times I don't weigh BPM all that heavily compared to stuff like EPM and LEBRON. For the 74-96 period it's one of the best stats we have though.

Ehhhhh, I'd be careful using it as a historical player evaluator. It's basically a pure box thing like PER/ws/48 pre-97 and even the years right after would be affected by the priors. Additionally, since we dont even have all the stats for historical players from the 70's, older players get underrated

Here's a page explaining BPM 2.0 on bkref where it goes over the formula. https://www.basketball-reference.com/about/bpm2.html . Whole bunch of things going on there.

You have to be aware of the shortcomings of stats like BPM but they still paint a better picture than the raw box numbers. Just going off WOWY type stuff for older eras is too limited imo.

[OhayoKD]

Here's a page explaining BPM 2.0 on bkref where it goes over the formula. https://www.basketball-reference.com/about/bpm2.html . Whole bunch of things going on there.

Okay looking at the defensive side of this, I'm seeing some red-flags:

How does Box Plus/Minus evaluate players? The basic concept is simple. BPM starts by assuming that every player on the team has contributed equally. If the team is good, all of the players are assumed to be equally good.
Next, the box score information is added to revise the evaluation. All of the box score data is measured relative to the other players on the team. Does this player get more or fewer steals than the other players on the team? If more, this player is likely better on defense than they are. Do they score more or less efficiently? Do they have more or fewer assists?

To be blunt, getting a bunch of steals has very little correlation with good defense, on a team, or individual level. Last season for example, of the 6 teams with the most steals per game, 3 had good defenses, 1 had an average defense, and 2 had a bad one.

Looking at last seasons's steal leaders:
https://www.landofbasketball.com/year_by_year_stats/2021_2022_leaders_steals_pg_rs.htm#:~:text=Who%20averaged%20the%20most%20steals,Leaders%20this%20season%3A%2058%20games.
IIRC, most of these players don't grade out as elite defenders via something like EPM(unfortunately last seasons's EPM data is no longer publicly available so I'm working off memory here). Using the prior defenders who get more steals are likely better than defenders who don't is kind of concerning since, going positionally, guards usually get the most steals, and they also happen to be(at least using a EPM metric as a baseline), the least valuable defensively.

I think what they're doing with blocks here is an even bigger red-flag:

This box score information is also weighted according to what position or role the player has on the team. For instance, a block by a center is good, but a block by a guard is great.

The problem here is that blocks from smaller players are often more a result of a bigger teammate's assistance than vice versa...(from a reddit post by ftd)

Why would you compare hakeem with pj tucker? The idea is that players who are racking up steals and blocks are going to be treated by box-metrics like dpoy-level defensive contributors, which is why your jordan's, kobe's and curry's look much better relative to other all-time greats when you focus on the box and less so when you focus on how the team defense correlates with their presence. One of the things bigger defensive players do is generate opportunities for smaller to rack up steals and blocks in the first place

We talk about gravity on offense, but what about defensive gravity? As I said before, Ben touches on the concept when he notes that Walton affected more possessions than Kareem despite Kareem getting alot more blocks, but this reaches a whole new level with players like Larry Bird or 6'6 shooting guard MJ, players who spent their defensve primes playng with one or multiple comparable-better rim deterrents.

This is what most jordan blocks look like:https://youtu.be/fFPi95UEpog?t=55 Jordan gets the block, but is he even the key to this possession? The difficult part of this, holding ewing still, isn't being done by Jordan. Jordan is making this play off his teamamte's, gravity defensively. If you rewatch the section where ben is fawning over Jordan's rim protection...

https://youtu.be/p5aNUS762wM?t=1212

...you might notice that aside for --two-- clips, all these plays have jordan making plays on a defender whose preoccupied worrying about a larger guy at the rim.

Lets compare this to the following non-blocks:https://youtu.be/T-c1NradPN4?t=147Lebron's presence here blows up a potential dunk/layup, a shot even more dangerous than a curry three. Lebron isn't awarded a block here, but this play is more valuable than the majority of plays you'll see in a jordan defensive highlight reel.https://youtu.be/T-c1NradPN4?t=17Lebron here basically prevents a open layup/dunk. These kinds of plays are both extremely valuable and require a combination of strength and size Jordan doesn't have.https://youtu.be/T-c1NradPN4?t=176Here, Lebron isn't rewarded a block and even looks a bit silly, but his presence is what draws draymond's attention and allows for delly to get the block.https://youtu.be/3oAAcEQ8t84?t=1529Lebron ends up getting a block later on the possessions, but the key of this possession is here, where Lebron's presence makes dwight opt for a post up, preventing what is the most dangerous play in basketball, an all time interior threat coming in at the rim. Per r/blockedbybam, Lebron blocked, diverted, or deterred a dwight inside atempt 18 times over the ECF..https://youtu.be/MyWFllfRqaU?t=256.Grant gets the block, and pippen is made to look silly, but it's pippen who sets the play up for grant. Much like a shooter will feed of a slasher's interior gravity, grant makes this play off pippen's defense.https://youtu.be/C7uxePXXfU8?t=63While the possession doesn't end up going chicago's way, what Pippen is doing here, essentially pre-emptively nuetralizing the threat of an Ewing drive is about as valuabe as a play you will get defensively. It doesn't show up in the scoresheet.

Gobert stops a layup here but he doesn't touch it so no credit

Generally, if we look at raw impact/wowy, or even things like LEBRON or RAPM(or even the more boxy PIPM), Guards posting comparable blocks per games to wings usually aren't actually generating more defensive impact. Yet BPM is essentially rewarding smaller defenders for making less valuable plays. This is how you get something like Larry Bird DBPM = Pippen

You have to be aware of the shortcomings of stats like BPM but they still paint a better picture than the raw box numbers. Just going off WOWY type stuff for older eras is too limited imo.

[/quote]
WOWY may be limited but it isn't going out of its way to skew towards certain positions(let alone a position which everything says is the least valuable), and you can use knowledge/other signals to expand its use. How exactly do you adjust for dbpm without just chucking it? Feel like when possible you should go by impact signals defensively to supplement the offensive stuff, even if you value bpm for "stable" offensive stuff. That alone will probably adjust a bunch of stuff.

Other thing is bpm's formula is based on incomplete data which will bias things agaisnt pre 80's players. Imo, BPM is just there as a last resort and i'd still just look at offense tbh. Defensive stuff is acctively going out of its way to mislead you.

[f4p]

WOWY may be limited but it isn't going out of its way to skew towards certain positions(let alone a position which everything says is the least valuable), and you can use knowledge/other signals to expand its use. How exactly do you adjust for dbpm without just chucking it? Feel like when possible you should go by impact signals defensively to supplement the offensive stuff, even if you value bpm for "stable" offensive stuff. That alone will probably adjust a bunch of stuff.

i can't confirm if he's right or not, but Dutchball97 is saying...


BPM gets calculated as a whole and then they try to single out how much of that comes from the offensive side and whatever value is left gets dumped on DBPM, at least that's roughly how it works.

...that OBPM and DBPM don't exist. BPM is the actual calculation. if jokic is a 12 BPM, then after that it just tries to figure out if it should give him 7 OBPM and 5 DBPM or 11 OBPM and 1 DBPM.

Other thing is bpm's formula is based on incomplete data which will bias things agaisnt pre 80's players. Imo, BPM is just there as a last resort and i'd still just look at offense tbh. Defensive stuff is acctively going out of its way to mislead you.

how do we know it's biased for or against the pre-80's players? wouldn't it depend on whether they were good or bad at the un-recorded stats?

[Saints14]

What I meant was don't use DBPM as a stat in itself but I'm not someone who disregards BPM as a whole because of it. I've seen people only use OBPM for offense but I value BPM as a catch all stat too as long as you're aware it's not the best at measuring defensive impact. Although I think it goes for every single stat that you need to take the formula into account like what it overvalues or undervalues compared to other stats. Every stat has value but no stat is gospel kind of thing.

Could you explain what you think the value of using dbpm is instead of just keeping the obpm and chucking the rest? Like couldn't you just look at steals/blocks/rebounds if you wanted that granular context?

It's a tough one and I can't give a definite answer to this to be honest. OBPM and DBPM aren't calculated seperately. BPM gets calculated as a whole and then they try to single out how much of that comes from the offensive side and whatever value is left gets dumped on DBPM, at least that's roughly how it works. It's just a bit messy and I'm not sure if it means OBPM is inherently more trustworthy than BPM itself.

I do like to incorporate as many stats as possible in my evaluations but for modern times I don't weigh BPM all that heavily compared to stuff like EPM and LEBRON. For the 74-96 period it's one of the best stats we have though.

I think this is correct, and that also the interaction of REB x AST is used as a positive indicator for defense, because historically that would more fit the profile of a versatile defensive wing. Over the past 5 years or so Westbrook, Harden, Jokic and Luka have kind of broken that, so I do wonder how often the model gets refitted

[OhayoKD]

WOWY may be limited but it isn't going out of its way to skew towards certain positions(let alone a position which everything says is the least valuable), and you can use knowledge/other signals to expand its use. How exactly do you adjust for dbpm without just chucking it? Feel like when possible you should go by impact signals defensively to supplement the offensive stuff, even if you value bpm for "stable" offensive stuff. That alone will probably adjust a bunch of stuff.

i can't confirm if he's right or not, but Dutchball97 is saying...


BPM gets calculated as a whole and then they try to single out how much of that comes from the offensive side and whatever value is left gets dumped on DBPM, at least that's roughly how it works.

...that OBPM and DBPM don't exist. BPM is the actual calculation. if jokic is a 12 BPM, then after that it just tries to figure out if it should give him 7 OBPM and 5 DBPM or 11 OBPM and 1 DBPM.

So does the DBPM component contain offensive value it shouldn't then? And then in what part of the calc process is stuff like "what position is the block coming from" and "steals relative to teammates" coming in? That should affect dbpm on its own right?

Other thing is bpm's formula is based on incomplete data which will bias things agaisnt pre 80's players. Imo, BPM is just there as a last resort and i'd still just look at offense tbh. Defensive stuff is acctively going out of its way to mislead you.

how do we know it's biased for or against the pre-80's players? wouldn't it depend on whether they were good or bad at the un-recorded stats?

[/quote]
Well, at least for something like blocks or rebounds, there isn't a "negative" counterpart its counting(missed rotations, defensive errors, ect aren't recorded in the stuff its using), so increased volume should see the score go up. I suppose that's not neccesarily the case for something like scoring or playmaking. (I'm also not sure how exactly the "lack of data" is distributed though i think i've read rebounds/blocks are the stuff thats mainly undercounted here)

[clearlynotjesse]

Everyone should probably just read the post where the creator of BPM explains everything about BPM: https://www.basketball-reference.com/about/bpm2.html The values and flaws of a box score only estimation of RAPM are laid out very clearly.

BPM is cool, especially for pre-pbp players, but it has broken before (2017 Westbrook) and will probably break again as box scores skew farther and farther away from what we were used to in the early days of +/- models. There are probably hundreds of SPM models that take advantage of all the modern data we have for modern players, use those instead.