Calculating relative ORtg/DRtg over a stretch of games

[thebottomline]

I've noticed in the peaks project that people are calculating relative ORtg and DRtg over certain stretches of games. For example, ElGee calculated that the 95 Bulls' ORtg was +5.6 in the 18 games with Jordan compared to +2.1 without him.

I've been trying to calculate some stuff on my own using b-r's box scores but I can't seem to get my spreadsheet to churn out the same numbers as everyone else's, so I'm wondering: how are you guys doing this?

[nikomCH]

+1

[ElGee]

You have to calculate pace over x number of games. Most people make the error of averaging pace, but this won't give you the number of possessions because each game doesn't have the same number of minutes (overtime).

The simplest way is to sum the team totals (you can use BR team game logs) and then apply the pace estimation. This will then give you a total number of possessions so you can calculate points/possession. Then you need to compare that to the defensive environment -- in this case, the average DRtg of the team's opponents over the stretch of games.

For the last 17g of the 95 season (Jordan in), the Bulls played 1570.8 pos and scored 1770 points...for an ORtg of 112.7, or +4.9 pts/100 relative to their opponents. If we include the PS we'd get something like:

95 Jordan IN: +5.0 ORtg (6.3 SRS) for 27 games
95 Jordan OUT: +1.2 ORtg (3.7 SRS) for 65 games

Hope that helps.

[thebottomline]

Thanks! Failing to account for OT is what was throwing me off.

[nikomCH]

Is there a way to calculate a team's ORtg and DRtg when a certain player is on and off the court? Not for games missed but just to see how much effect a player actually has when he enters or leaves the game

[nikomCH]

Old ass thread but bballref game logs provides the ORtgs for both teams (and thus the DRtgs as well). Why couldn't one just add up those numbers and divide by # of games to get an average ORtg or DRtg over a stretch of games instead of manually calculating points and pace?

[mysticbb]

Because it is easier to use the team gamelog and match that up with the player gamelog, while then calculating possessions by yourself, than going through each of the boxscores, check whether the player played or not and then collect the ORtg/DRtg to build an average (with the correct weight!).

[nikomCH]

But what if you're just looking for the ORtg/DRtg for the entire team and not concerned about whether a certain player was there or not? Is there still a flaw with only averaging up the already calculated ORtgs and DRtgs?

Also by "calculate possessions" what do you mean? Do you mean just add the up the pace numbers provided in the box score?

[mysticbb]

http://www.basketball-reference.com/tea ... 3/gamelog/

That is a team gamelog. I have all things I need to estimate the amount of possessions for each game. Then I can simply sum up the points and possession while then devide points by possessions mulitply by 100 and get ORtg/DRtg.

The formula for the poss can be found here: http://www.basketball-reference.com/about/glossary.html

So, as you can see, it is just copy&paste of the team gamelog instead of clicking through the boxscores, much simpler and is way faster.

(Tbh, I have all team gamelogs in a database of my own already, but that is a different story.)

[nikomCH]

Got ya, didn't realize it was that easy to paste into a spreadsheet (thought it would be all jumbled)

Now all I need to figure out is how to create that possessions formula in Excel

[mysticbb]

Now all I need to figure out is how to create that possessions formula in Excel

Shouldn't be that difficult. One thing to remember, the gamelogs don't have drb listed, but drb = trb-orb. ;)

[lorak]

And b-r game log also don't have team RBS or TOV, so ortg calculated based on game log would be slightly different than what they have on team page.

[ardee]

On a slightly different note but yet related... Is there an easier way to run an in-out then simply pulling up team logs and player logs and figuring out which he missed? Is there a list of missed games on some site?

[FlutieX]

I've been wondering this myself, very informative post.