courtney lee and leandro barbosa: this isnt going to cut it.

The real depressing stat is that we improve just as much offensively when Courtney Lee goes to the bench as we do when Rondo gets on the court.

Ouch!!!

Nice post! Such a nice post. TP 4 you!

Okay I did some digging and found out that most teams have a guy like Lee. Guys that are useful but have terrible +/- numbers. Here are a few examples from winning-ish teams:

Harrison Barnes
Caron Butler
Mario Chalmers/Norris Cole
Borris Diaw
Kendrick Perkins
Steve Novak/Cory Brewer

There are guys who are doing important things but just don't have good +/- numbers. That is probably Lee. He needs to shoot better and find a way to integrate himself into the offense. He'll probably get better as our rotations solidify.

Barbosa is a 3rd string player and that isn't an abnormal number for 3rd string players. Collins +/- is even worse from what I've seen and he's probably our bigger problem. We're starting a guy who is putting up 3rd string numbers. Have no fear I'm sure Danny knows how to read a +/- sheet.

Why thank you 

I think the Off/Def rating is actually a bit different to the +/- rating.

+/- only takes into account how much the lead increases / decreases when a player steps on/off the floor.  I imagine that this could be very strongly affected by the teams rotations - for example Boston had a certain player who always came in and out of the game the same time as KG, thenhe would probably have a very strong positive +/- but it would be because of KG's play, not because of his. 

The Off / Def ratings however IIRC are based on fomulas that focus more on the individuals performance: 

Offensive Rating:

"Offensive Rating" is a statistic used in basketball to measure either a team's offensive performance or an individual player's efficiency at producing points for the offense. It was created by author and statistician Dean Oliver.
 
For players, the formula is: Offensive Rating = (Points Produced / Individual Possessions) x 100
 
Points can be produced through field goals, free throws, assists, and offensive rebounds. Individual possessions are the sum of a player's scoring possessions (field goals, free throws, plus partial credit for assists), missed field goals and free throws that the defense rebounds, and turnovers.

Defensive Rating

Defensive Rating is a statistic used in basketball to
measure an individual player's efficiency at preventing the other team from scoring points.

The formula is: Defensive Rating = (Opponent's Points Allowed/ Opponent's Possessions) x 100. The result is the expected amount of points that an individual player will allow on defense over 100 possessions.

Chalmers actually has a very strong positive net rating or +13.4, but the others you listed do indeed have negative ratings. 

I think I know why Lee's numbers are so unimpressive, even though according to the eye test, it looks like he's doing pretty well. 

I've noticed in the last few games that Lee actually plays pretty solid individual defense, however he appears to be very poor at team defense. 

I've noticed lately that he will man up his defensive assignment nicely when they have the ball, but he is incredibly bad at reacting to defensive rotations, especially on three point shooters.  He'll wait until a player catches the ball before he even begins to run at them, and by the time he gets close they have already released the wide open shot.  Last game against Golden State I was vaguely keeping count and there were at least 3-4 three point shots that were scored against Lee's slow rotations.  May not seem like a lot, but that's 9-12 free points he's essentially given up to the opposing team.

I was watching Terry in the same game, and although his on-ball defense doesn't look as aggressive as Lee's, Terry is actually very sharp with his team defense and reacts very quickly to roations.  As soon an opposing player begins to make a pass he has identified who it's going to and he immeidately begins to rotate over - by the time the defense catches the ball Terry has a hand in his face and has affected the shot. 

What does shoot better even mean? He's shooting a career high FG%, was shooting over 50% from the field in the month of December until that crappy game in Sacramento, still 46% for a month is quite solid.

Anyways, I don't care much for on and off analysis... there's too much noise in those numbers for me to give them any credibility.

These stats are Off/Def ratings and not on/off stats.

As described above I think Lee's negative def rating is due to his horrible defensive rotations on opposing shooters.  I think his negative off ratings is do to a combination of high turnovers, plus the fact that he just doesn't do a lot on offense - doesn't take or make enough shots to be a major factor in the majority of games.

I don't even care much about the offensive stats, I'll go right to the defense.

Brandon Bass and Courtney Lee either play better or they HAVE TO GO.

Jason Terry and Jared Sullinger are defensive savants considering after KG, they're boasting the best defensive ratings on the team.

5% of the time analytics can make sense, most of the time you see stuff like this.

I think it's not so much a case of the numbers being innacurate as it is a case of people just not wanting to accept what they see. 

For example I checked these stats back when Courtney Lee was starting alongside KG and he still had a similar defensive rating, so going to the bench hasn't really changed it.

Courtney Lee just isn't the lock-down defender people believe him to be.  Lets look at his historic statistics:

* 2012 - 2013 Boston Celtics (+3.26)
* 2011 - 2012 Houston Rockets (-0.75)
* 2010 - 2011 Houston Rockets (+0.9)
* 2009 - 2010 New Jersey Nets (+5.58)
* 2008 - 2009 Orlando Magic (+2.18)

With the exception of last season with the Rockets, Lee has had a below average defensive rating every single season that he's been in the league.  Even the one good defensive season he had (last season) strayed barely above neutral.  He is pretty much an average defender at best, and a mediocre defender at worst.  Again this doesn't surprise me at all given how many open three's I've seen him allow over the last few games.

Also there is no pattern here at all to suggest that the figures are strongly affected by who someone plays with. 

Bass has started the majority of this season alongside KG, yet his defensive rating is the second worst on the team (+6).  Last year his defensive rating was similarly poor (+3), despite him being a starter on an elite defensive team.  In the playoffs his defensive rating was identical to this seaon (+6) so the numbers show that Bass has been hurting us on defense as long as he's been in a Celtics uniform.

I've noticed that Sullinger struggled defensively at the start of the season, but he has been playing very solid defense for about the past 10 games.  Sure enough he has a good def rating right now despite the fact that he's spent most of this season coming off the bench, and when I checked his stats about a month or two ago he had a below average rating (around +3).

Paul Pierce and Rajon Rondo - both bonafide starters - both have slightly negative defensive ratings despite spending most of their time on the court with KG.

Jeff Green has been purely a bench player this season and is often on the court without KG, yet his defensive rating is neutral. In fact ironically it looks like Green's defense has improved as a Celtic, because he's had better defensive ratings in both 2010 and 2012 then he ever had in OKC:

* 2012-2013 BOS (+0.02)
* 2010-2011 BOS/OKC (+4.72)
* 2009-2010 OKC (+10.61)
* 2008-2009 OKC (+5.76)

Need more proof?  Ray Allen was mostly healthy during the reg season last year, but people had noticed his defense had declined with age.  In the playoffs he was hurt and his defense dropped from below average to simply horrendous.  This season he has been notoriously bad on defense for Miami.  The numbers reflect this accurately:

* 2012-2013 Season MIA (+9.00)
* 2011-2012 Playoffs BOS (+10.23)
* 2011-2012 Season BOS (+4.94)
* 2010-2011 Season BOS (+1.68)

Some people are complaining that Terry was a better defensive player in Dallas, but has struggled here.  The stats say otherwise:

*2012-2013 Season BOS (-4.88)
*2011-2012 Playoffs DAL (+7.53)
*2011-2012 Season DAL (+5.88)
*2010-2011 Playoffs DAL (+3.12)
*2010-2011 Season DAL (+3.13)
*2009-2010 Season DAL (+0.32)
*2008-2009 Season DAL (+1.15)
*2007-2008 Season DAL (+2.16)

Terry has been a consistently average or below average defender in his past 5 seasons with Dallas, yet this season in Boston his statistics suggest he has been significantly above average.  Dallas were never a defensive oriented team so maybe Terry has benefitted greatly coming to a team with a defensive coach and culture.  Either way Terry has spend just as much time with KG as he has without, so KG's presence doesn't explain his good defensive numbers.

Surely there is room for other players to impact the numbers to some small degree - if the lineup is full of poor help defenders and you let your defender get by you, they will most likely score.  If your lineup is full of great help defenders and you let your defender get by you he probably won't score due to quality help defense, and whether or not your assigment scores would impact on your defensive rating. 

Still, based on individual numbers there doesn't appear to be any pattern suggesting that players who are on the court with KG have got better defensive ratings. 

It's not just on defense either - it's the same deal on offense. 

Kevin Garnett spends the majority of his time on the court with Rondo, Pierce and Terry - Boston's top offensive players.  Despite this fact, KG has a negative offensive rating this season.  Last season KG was a +9.56 on offense when playing alongside Rondo, Pierce and Ray Allen.  This season he is a -4.88 when playing with Rondo, Pierce and Terry.

Jason Terry is a +3.29 on offense this season and Ray Allen was a +4.45 on offense last season.  Very little difference between the two, so I can assure you Ray Allen was not the reason for KG's -14.4 drop offensively. 

Jared Sullinger and Chris Wilcox both have positive offensive ratings despite the fact that both have been almost exclusively bench players.  In fact they are the only two guys on the bench who have positive offensive ratings (Bass has been a starter for most of the season).

This is why I think these numbers aren't as biased as people think.  There just isn't enough consistency there to suggest that the player's numbers are skewed depending on who they play with.