Rebounding Theory

[Rondo2287]

Watching the Thunder last night, I saw a ton of times where Ibaka, Durant and either Collison or Perk were on the floor where Denver would take a shot and before it even hit the rim everybody would run back on defense.  I have noticed this in several other games too, not just this one, but it is was especially prevelant last night.

My theory is that against certain teams the opposing team knows their chances of getting an offensive rebound so they don't really try that hard to get one and risk being out of position in transition. 

When teams are playing the celtics they smell blood in the water and know if they send 2 guys to the boards they probably have at least a 20% chance of getting an O-reb.  I think that what the Perkins trade may have really done is take that fear out of the celtics opponents because Perk was also good at getting the ball to Rondo quickly so he could punish teams in transition.  Thoughts?

[LooseCannon]

Even the worst offensive rebounding teams of the past two seasons have had at least a 20% offensive rebounding percentage, so any team has at least a 20% of grabbing an offensive board.

Pop quiz, hotshot.  If your theory about teams no longer fearing the Celtics is right, should this year's Celtics have a defensive rebounding percentage that is higher, lower, or about the same as last season's?

[Rondo2287]

Even the worst offensive rebounding teams of the past two seasons have had at least a 20% offensive rebounding percentage, so any team has at least a 20% of grabbing an offensive board.

Pop quiz, hotshot.  If your theory about teams no longer fearing the Celtics is right, should this year's Celtics have a defensive rebounding percentage that is higher, lower, or about the same as last season's?

Right but against the best defensive rebounding team the worst offensive rebounding team wont have a 20% success rate right? 

And I have no idea, but if you can give me those numbers for the second half of these season i would be intereseted.  I know that over the past few years the celts have been one of the worst rebounding teams in the league, im just saying it seems like teams have no fear in hanging around the rim against us.

[Greenbean]

It was obvious that the Knicks were crashing the offensive glass the other night.

There is a reason their transition D was absolutely terrible. The Celtics had 12 more fastbreak points than the Knicks (16 to 4), a running team. Also Rondo was either on the fast break or a secondary break for virtually every play. The tradeoff was 2nd chance points.

Alot of teams take this approach with the Celtics and other defensive minded teams. Frankly its the only chance they have. The Celtics just need to improve their percentage of snatched defensive boards when teams try to do this. Its not always easy. The ball bounces in funny directions sometimes and after several crisp defensive rotations, it isnt always easy to box out.

After Rondo's 30 point outrburst the other night, Im guessing the Knicks will not be going back to this strategy. Look for rebounding numbers similar to game 1.

[Moranis]

Garnett is still by far the best rebounder in the series.  Rondo is the best rebounding guard.  Melo is really the only position that the Knicks hold a rebounding advantage.  The Knicks just went all out and that left open the fast breaks.  I'm ok with that.  If the Knicks want to go all out and let the Celtics get easy baskets in transition, fine with me.

[LooseCannon]

Right but against the best defensive rebounding team the worst offensive rebounding team wont have a 20% success rate right? 

I actually would guess they would.

And I have no idea, but if you can give me those numbers for the second half of these season i would be intereseted.  I know that over the past few years the celts have been one of the worst rebounding teams in the league, im just saying it seems like teams have no fear in hanging around the rim against us.

Lots of stats are available at basketball-reference.com

[Rondo2287]

Right but against the best defensive rebounding team the worst offensive rebounding team wont have a 20% success rate right? 

I actually would guess they would.

And I have no idea, but if you can give me those numbers for the second half of these season i would be intereseted.  I know that over the past few years the celts have been one of the worst rebounding teams in the league, im just saying it seems like teams have no fear in hanging around the rim against us.

Lots of stats are available at basketball-reference.com

Your wrong, the worst team offensive rebounding team would not average 20% offensive rebounds against the best team, its a statistic impossibility if your numbers are correct.

However thats not really the point of this thread hotshot

[Who]

And I have no idea, but if you can give me those numbers for the second half of these season i would be intereseted.

 I know that over the past few years the celts have been one of the worst rebounding teams in the league, im just saying it seems like teams have no fear in hanging around the rim against us.

The Celtics had a defensive rebounding percentage of 74.6% before the All-Star break (first 56 games) and a 74.8% defensive rebounding percentage post All-Star break (final 28 games).

They had a rebounding differential of -0.7 per game pre All-Star break and a differential of -1.1 post All-Star break.

The difference being Boston's misfiring offense led to more missed shots without an increase in offensive rebounding (a decrease actually from 21.5% to 20.3%) so the other team got slightly more defensive boards than earlier in the season.

In wins versus losses, the C's go from a +1.2 rebounding differential to a -5.2 differential. Huge difference (6.4 rebounds per game). I wonder if that is true for other teams. I presume there is a big difference (rebounding differential from wins to losses) but I wonder if it is that large. 

[Marcus13]

All sports are as much mental as physical.

So if you're intimidated by a team's frontcourt (like the entire league other than the Lakers were), then it's going to change the way you physically play the game.

[Who]

In wins versus losses, the C's go from a +1.2 rebounding differential to a -5.2 differential. Huge difference (6.4 rebounds per game). I wonder if that is true for other teams. I presume there is a big difference (rebounding differential from wins to losses) but I wonder if it is that large. 

Just a quick comparison:

(1) Lakers - wins +3.6, losses -0.1, difference 3.7
(2) Miami - wins +5.9, losses -4.2, difference 10.3
(3) Chicago - wins +7.3, losses +0.9, difference 6.4
(4) Spurs - wins +1.6, losses -3.1, difference 4.7
(5) Mavs - wins +2.7, losses -3.8, difference 6.5
(6) Magic - wins +6.5, losses -1.7, difference 8.2

Okay, so that rebounding difference from wins to losses for Boston looks fairly similar with a couple of other elite teams (Dallas, Chicago).  Some teams are more consistent on the boards (Lakers, Spurs) through wins and losses while others vary even more from wins to losses (wow, Miami).

[LooseCannon]

Your wrong, the worst team offensive rebounding team would not average 20% offensive rebounds against the best team, its a statistic impossibility if your numbers are correct.

Please explain how it is an impossibility.

In order to get a larger sample size, I looked regular season games played between one of the top 3 defensive rebounding teams and one of the bottom 3 offensive rebounding teams.  In those 26 games, the bad rebounding teams combined for 212 offensive rebounds while the good rebounding teams had 829 defensive rebounds (with the caveat that I could have arithmetic errors).  The bad offensive rebounding teams grabbed about 20.4% of the rebounds off their misses.

The top team in DR% in recent years seems to be in the 77-78% range.  I think it's plausible to suggest that if you almost complete abdicate on offensive boards, you're still going to have a baseline 20% OR percentage, or nearly so, just based on players rebounding their own misses or the ball caroming directly to an offensive player.  Of course, that's over the long-haul and individual games are small samples that can swing wildly.

[GranTur]

I think that what the Perkins trade may have really done is take that fear out of the celtics opponents because Perk was also good at getting the ball to Rondo quickly so he could punish teams in transition.  Thoughts?

Celtics have had rebounding problems for a couple years now...

KG, Shaq, and JO are all better rebounders than Perk anyway.

[Chris]

I think the C's rebounding woes come from a few different areas.

First, they really don't have many great rebounders in the frontcourt.  While KG, JO, and Shaq were always good to great rebounders when they were younger, they have all lost at least a step or two, so they aren't what they used to be.  And Davis, Green, and Krstic are all below average rebounders for big men.

Second, the system is not built for big men rebounding.  They don't do a ton of offensive rebounding, mainly because they emphasize getting back on defense so much, and defensively, the system pulls the big men away from the basket so much in order to help on the perimeter, which leaves them out of position to box out the big men who might be rolling and crashing the boards. 

Third, the system relies a lot on the perimeter guys crashing down and grabbing a lot of rebounds (which is why the C's were at their best last year when Pierce and Rondo had a lot of rebounds).  This is compounded by the fact that their PG happens to be at his best when they can get out on the break, which means the perimeter guys need to leak out early to get behind the defense, leaving the C's vulnerable on long rebounds.

Now, in game 2, I think we saw a perfect storm of all of these factors combining to really kill them.  The personnel issues are obvious, but they were even worse than normal because of JO being in foul trouble, as well as the Knicks matchup forcing them to go smaller for long portions of time with Green at the PF spot. 

They also were taking their help defense to the next level later in the game by using Davis as essentially a roamer to double-team Melo anytime he got the ball, which left him completely out of position to block out his man once the shot went up, and he is not big enough to overcome that (I also think this defensive strategy was part of the reason we didn't see JO late in the game, because Davis has quicker feet to blitz and get back to defend).

And finally, the C's perimeter guys were leaking out more than normal in the hopes of righting the ship offensively.  There were many times when Rondo, Pierce and Allen were way behind the defense, which means they were not going down to help on the boards...which was especially bad since NYK were launching a lot of 3's, leading to long rebounds, which are always the perimeter players domain.

Anyways, I don't think anything is going to change about the personnel.  We had similar issues last year even with Perk, and this team just are what they are, but there are some changes Doc can make to improve their rebounding.  The tough part is going to be how to do that without sacrificing the defense, or the offense, which was finally showing some life last game.

[action781]

I'm sick and tired of everyone talking about the Celtics' problems rebounding and that being a cause for their struggles.  It's mentioned much on this blog and I just heard the ABC analysts discussing it.  I think it is mostly garbage.

Whenever people discuss it, the statistic always analyzed is simply the number of rebounds per games.  Boston is 29th in the NBA in with 38.81 rebounds per game.  That sounds TERRIBLE.  But some other stats shed more light onto what kind of rebounding team we really are:

-Boston is 20th in the NBA in rebounding differential at -0.73.  That means we are outrebounded by less than one per game on average.
-Boston is 5th in the NBA in defensive rebounds allowed per game.
-Boston is 8th in the NBA in offensive rebounds allowed per game.
-Boston is 2nd in the NBA in total rebounds allowed per game.

Another thing I'd like to mention is that our low rebounding numbers are actually by design.  Our total rebound numbers are as low as they are because the celtics have been instructed to not attack the offensive glass and instead to get back to prevent transition offense.  That is why the celtics are dead last in the NBA in offensive rebounding % (edit: fixed) but also are second in the NBA in fast break points allowed per game at only 10.9.  So the celtics coaching staff has decided:  total rebound per game numbers are not as important as fast break points allowed per game and we are going to sacrifice rebounds for transition defense.

If we're, on average, giving up more rebounds than we collect (i.e., the negative rebound differential), then I think that's a problem.  As good as we are at defense, we should be outrebounding other teams, because we create more defensive rebounds.

We're currently 8th in the NBA in defensive rebounding %.  That is a very high ranking for a "bad rebounding team" at grabbing 74.8% of available defensive rebounds.  The Lakers, who everyone seems to consider the model of frontcourt strength and size, only grab 72.2%.  So, we are actually a better defensive rebounding team than the Lakers.  We are a far worse offensive rebounding team, but it is by design because our coaching staff values transition defense as a higher priority (Lakers give up 3 more fast break ppg than the Celtics do).  We have a differential of +1.9 defensive rebounds per game.  

Celtics like to play a slower halfcourt game.  So, first of all, total numbers for BOTH teams are going to be down in terms of rebounding in those games.  That's why I think % is a more valid statistic to consider that total #'s.

[action781]

Your wrong, the worst team offensive rebounding team would not average 20% offensive rebounds against the best team, its a statistic impossibility if your numbers are correct.

However thats not really the point of this thread hotshot

http://www.teamrankings.com/nba/stat/offensive-rebounding-pct

The worst team in the NBA in offensive rebounding % is Boston at 21.4%.  So, it's absolutely possible that the worst rebounding team could average 20% offensive rebounds against the best team.  That's because what the "best" team here is interpretive.  Best what?  Best team?  Best overall/offensive/defensive rebounding team? 

Also, rebounding can have a lot to do with matchups.  Some bigger and slower players might have more success boxing out against Perk than Amare, while the two players have near equal rebounding numbers.  So, yes, the worst team in the NBA in offensive rebounding could definitely average 20% offensive rebounds against the "best" team, no matter what that is decided as.