Can someone explain this to me?(NBA question)

[Assani Fisher]

82games.com has a feature where you can see how a guy's team does on both offense and defense with him compared to without him. They use "points per 100 possessions" to show this.

To give an example:

With Antonio McDyess on the floor, Detroit averaged 111.0 points per 100 possessions and gave up 102.7 points per 100 possessions.

Without McDyess on the floor, Detroit scored 108.7 points per 100 possessions and gave up 106.7 points per 100 possessions.

Therefore McDyess' offensive net is +2.3 and his defensive net is -4.0.

His total would be +6.3, which is pretty damn good(I was actually surprised he was so effective).

Clearly its good to have a positive rating on offense and a negative rating on defense.



Now I'm sure that many of you already know all that, so forgive me but I just wanted to throw it out there for anyone that didn't. Now onto my question....

Skip ahead to here if you already know how 82games.com stats work

Here are the 10 guys that made the All Defensive Team this past year with their defensive nets displayed next to their names:

Raja Bell: -3.6
Kobe Bryant: -0.7
Tim Duncan: -6.5
Bruce Bowen: -9.6
Marcus Camby: +2.1
Kevin Garnett: -5.7
Kirk Hinrich: +1.9
Jason Kidd: +0.9
Ben Wallace: +2.4
Tayshuan Prince: +2.4

WTF? Five out of the ten guys had positive defensive nets? And defensive player of the year Marcus Camby was the worst at +2.7? This is even more troubling when you think about what a bad defensive team Denver is. How could it possibly be that Camby was a detriment to their defense?

Can anyone explain this? In the past few months I have started using these types of stats in a lot of my arguments, and this kind of makes me want to reconsider that. Or then theres the possibility that perhaps many of these guys simply aren't the defensive stoppers that we think, but they're getting by on reputation. Thoughts?

[kidcolin]

Assani,

I can't explain it off the top of my head, but 82games also has a good "DPOY" article, and they can concur that Camby and Duncan are in the top 3 (they had Marion winning it). That might offer some explanation.

Some base things to think about is lineups faced and time played. Lots of second unit guys with good +/- ratings tend to face weaker competition. So it's easier to score AND they're not as good at scoring.

Another factor is the lineup you play with. There was some neat +/- numbers in the Finals where Donyell Marshal was rating well. It was more of an indication that the Cavs were successful when they went with the small lineup rather than Donyell rules.

[MicroBob]

Similar to kidcolin's observation: I wonder if some of those stats could be really skewed by the 5-10 last possessions of blowout games where teams aren't really trying as much or put in their scrubs.

DET up by 25 with 3 minutes left: Leaving McDyess in there to play it out when both teams have mostly stopped trying changes things some.
Or pulling him out and having a bunch of scrubs out there playing hard can change everyone's stats.
"OMG, DET scores more per possession when all their bench players are in!!"


A speedy defensive sub who gets a higher than normal percentage of his minutes in games where they are trailing late is going to have a really crappy +/- ratio I suspect.
He'll get in there with 1 minute left down by 6 with the sole purpose of fouling a defending player.
Yet when his team has the ball they are going to be more likely to force up lower percentage shots.

Anyway, you get the idea. I think there night be lots of ways these stats can get skewed....not all possessions are created equal...blah blah blah.

[KLJ]

[ QUOTE ]
Similar to kidcolin's observation: I wonder if some of those stats could be really skewed by the 5-10 last possessions of blowout games where teams aren't really trying as much or put in their scrubs.

DET up by 25 with 3 minutes left: Leaving McDyess in there to play it out when both teams have mostly stopped trying changes things some.
Or pulling him out and having a bunch of scrubs out there playing hard can change everyone's stats.
"OMG, DET scores more per possession when all their bench players are in!!"


A speedy defensive sub who gets a higher than normal percentage of his minutes in games where they are trailing late is going to have a really crappy +/- ratio I suspect.
He'll get in there with 1 minute left down by 6 with the sole purpose of fouling a defending player.
Yet when his team has the ball they are going to be more likely to force up lower percentage shots.

Anyway, you get the idea. I think there night be lots of ways these stats can get skewed....not all possessions are created equal...blah blah blah.

[/ QUOTE ]

agreed. in addition, player combinations (maybe camby gets put with a group of weaker defenders), game pace (maybe camby gets put with faster players, and camby might excel in half court defense), game situation (early in the game, late in the game, etc).

[Assani Fisher]

I hear what you guys are saying, but over the course of a season this has to equal out somewhat, no?

"maybe camby gets put with a group of weaker defenders"...well AI and Melo play near the entire game. And theres no real great defender on Denver except for Camby.

I mean maybe I could buy your guys' argument for a role player who plays limited minutes. His minutes would be so small and in such specific situations that he could fall victim to this. However with a guy like Camby, it just doesn't make sense to me that the Nuggets would give up more points per possession with him in the game.

[MediaPA]

When Camby isn't in the game, it's generally the opponent's second string players on the court who are less efficient on the offensive end of the court - resulting in an even lower points per 100 possessions (despite weaker overall defense for the Nuggets than with Camby).

I mean it's just a stat. They are guidelines but don't tell the whole story always.

[KLJ]

[ QUOTE ]
I hear what you guys are saying, but over the course of a season this has to equal out somewhat, no?

"maybe camby gets put with a group of weaker defenders"...well AI and Melo play near the entire game. And theres no real great defender on Denver except for Camby.

I mean maybe I could buy your guys' argument for a role player who plays limited minutes. His minutes would be so small and in such specific situations that he could fall victim to this. However with a guy like Camby, it just doesn't make sense to me that the Nuggets would give up more points per possession with him in the game.

[/ QUOTE ]


what's his offensive net? i wouldn't think his offense is much (if any) better than neutral ev, so his defense could possibly lead to more points scored, rather than limiting points given up. who knows. just being a devil's advocate here.