To Crash or Not to Crash: Transition Def v Off Rebounding

#1      
I've complained a few times (maybe too many times) that I disagree with Groce's philosophy to send all (most) guys back on defense after the shot goes up instead of crashing the offensive boards (sending at least two or three). I know many of you disagree and that's ok.

I wanted to post this interesting study by MIT - "To Crash or Not to Crash: A quantitative look at the relationship between offensive rebounding and transition defense in the NBA".

And if you want to see the slides they're here:

I know this is an NBA study and not NCAAM but basically it says sending more players to crash boards instead of getting back in transition defense pays off, resulting in a net +4 points difference per game. And I know there are a ton of other caveats (style of play, your personnel, etc) but in general I agree that the gamble pays off more often than not. As bad as our transition defense is, our offensive rebounding is virtually non-existent which I think hurts us worse. I'll hang up and listen to your answer.
 
#2      
Washington, DC
The paper is just full of variables they consider "worth further study" that they just don't know how to evaluate. There is also this:

"Admittedly this analysis does not account for the personnel on a team. For example, some teams may not have two good rebounders. In such a case sending two players to crash and one player to retreat might not have the same expected gain as it does when we consider aggregate data from all teams. This is an opportunity for further analysis."

I am not sure Illinois has even one good rebounder. I think that makes the argument for getting back to avoid transition baskets all the stronger.
 
#3      
Just wanted to note that this is not really "Groce's philosophy", it's an adjustment he chose to make this season after Thorne was injured. I don't think he's adverse to going after the offensive glass under normal circumstances.
 
#4      
Thanks for the link! I've long been infuriated by Groce's stubborn refusal to send players to the offensive glass. If the Illini were an elite half court defensive squad (e.g., the Majerus-coached SLU teams who employed a similar tactic), this strategy would be more defensible, as it would severely limit the opposition's ability to score whatsoever. As it is, though, opposing teams are able to find high-percentage shots at will against our halfcourt D, eliminating the utility of forfeiting offensive boards. Glad to finally see solid analytics work supporting what appears logical when watching games.

On a similar note, is anyone else upset with self-professed "numbers guy" JFG frequently ignoring 2-for-1 situations? Choosing one possession over two is blatantly not a numbers-driven decision.
 
#6      
Washington, DC
Right, and sending bad rebounders to seek offensive rebounds at the expense of getting back on D is not going to produce many more rebounds but it is going to produce more easy baskets, and more fouls spent trying to prevent those easy baskets, on the other end.
 
#7      
Iowa City
Just wanted to note that this is not really "Groce's philosophy", it's an adjustment he chose to make this season after Thorne was injured. I don't think he's adverse to going after the offensive glass under normal circumstances.
Thank you. I was trying to figure out if we were doing this when Big Mike was playing. I can see some of the reasoning. Look at how the floor is spread when a shot goes up. 4 guys around the arch and 1 at the top of the key a lot of the time. No even close to be in a good position to get a rebound. Still drives me nuts when I watch a rebound land or go where we just had a guy standing, only to have his back turned and running down court.
 
#8      
Thank you. I was trying to figure out if we were doing this when Big Mike was playing. I can see some of the reasoning. Look at how the floor is spread when a shot goes up. 4 guys around the arch and 1 at the top of the key a lot of the time. No even close to be in a good position to get a rebound. Still drives me nuts when I watch a rebound land or go where we just had a guy standing, only to have his back turned and running down court.

I see the exact same thing. If they just hold their ground or take a step forward it's right there.

Also we shoot a TON of threes which often results in long rebounds when missed. With or without Thorne, he's not going to get those. Recall Dakich's comment during the Michigan game that he couldn't believe with all the missed shots, Illinois only got X offensive boards.
 
#9      
Thank you. I was trying to figure out if we were doing this when Big Mike was playing. I can see some of the reasoning. Look at how the floor is spread when a shot goes up. 4 guys around the arch and 1 at the top of the key a lot of the time. No even close to be in a good position to get a rebound. Still drives me nuts when I watch a rebound land or go where we just had a guy standing, only to have his back turned and running down court.

That's what I've been noticing, If they would have stayed put the ball would have fell right in their lap. Drive's me crazy.
 
#11      
I can certainly understanding the reasons to favor transition defense over offensive rebounding, especially given our personnel.

That being said, the truly frustrating thing for me is when there seems to be a lack of in-game adjustments when the commitment to transition defensive is obviously not helping. For example, I feel like the Indiana game was a perfect situation where Groce (or one of the assistants) would pretty quickly say "geez, they are nailing threes no matter what we do, maybe we should just try and fight for offensive boards and extend our defense a bit to see if we can disrupt their flow."

I'm sure they have these conversations and I would think there are tons of nuances and reasons they choose not to adjust (or maybe I don't notice), but as a fan it can be infuriating to watch!
 
#14      
Springfield
Some other interesting reading on the topic...

https://thecauldron.si.com/the-atlanta-hawks-secret-sauce-9d33719e5a48#.37pf4q4ln
- go about 1/2 down -- "Here’s Atlanta’s secret on defense:
2. Ignore the offensive glass to prevent early opportunities for opponents"

and http://genius.com/2995856 - article on pack-line defense -- "The first step to this defense is limiting fast-break opportunities. As soon as your offense misses the shot and gives up the rebound, the offense turns into defense. The team runs to the other side of the court in full sprint to set up its defense."
 
#15      
Some other interesting reading on the topic...

https://thecauldron.si.com/the-atlanta-hawks-secret-sauce-9d33719e5a48#.37pf4q4ln
- go about 1/2 down -- "Here’s Atlanta’s secret on defense:
2. Ignore the offensive glass to prevent early opportunities for opponents"

and http://genius.com/2995856 - article on pack-line defense -- "The first step to this defense is limiting fast-break opportunities. As soon as your offense misses the shot and gives up the rebound, the offense turns into defense. The team runs to the other side of the court in full sprint to set up its defense."

Good articles for sure. Groce definitely embraces the Pack Line and had hung his hat on defending the 3. One of the things I see is the inability and BBIQ to run the offense through leaving a floor imbalance. Breaking down Ohio he had some cerebral players who kept the floor balanced and used the options and reads off the O scheme that are not seen here. Seems like he is compensating by sending guys back rather than crashing boards. Some nice reading in the Pack Line explanation and with Mack, Miller et al easy to see their affinity based on the tree from whence they came.
 
#16      
Some other interesting reading on the topic...

https://thecauldron.si.com/the-atlanta-hawks-secret-sauce-9d33719e5a48#.37pf4q4ln
- go about 1/2 down -- "Here’s Atlanta’s secret on defense:
2. Ignore the offensive glass to prevent early opportunities for opponents"

and http://genius.com/2995856 - article on pack-line defense -- "The first step to this defense is limiting fast-break opportunities. As soon as your offense misses the shot and gives up the rebound, the offense turns into defense. The team runs to the other side of the court in full sprint to set up its defense."


I think the key quote in the first article is this:
Because the Hawks shoot the ball at such a high efficiency, they’re willing to sacrifice potential extra possessions from offensive rebounds if it means they can limit easy scores in transition for opponents.

That would not describe the Illini.
 
#18      
Captain 'Paign
Phoenix, AZ
If our defense wasn't such a turnstyle I could see this strategy making sense, but with the percentage of shots we miss I can't help but think we'd be significantly better off if we at least TRIED to get offensive boards. I can't imagine how many second chance points were are missing out on, not to mention limiting the number of possessions of our opponents.
 
#20      
I don't blame Groce for concentrating on getting back over O rebounding with this team. The only RBs we're going to get are the long ones and they're too unpredictable. My first priority for rebounding would be on the defensive end. We must lose 3 out of 4 long rebounds on the D end. Too much watching rather than seeking out guys to box out and guys crashing. And I don't see anyone very good at following the flight of the ball to anticipate where it's going. We have too many possessions where we need a stop, play good D as the clock winds down, force a hurried or bad shot, and then look helpless at corralling the long RBs coming off those shots. JMO.
 
#21      
I still have high faith in Groce, but this aspect as a coach is frustrating for me to watch. I don't understand how, when you're a team who is as bad as we are defensively, that we decide to not even attempt to get offensive rebounds with as many threes as we chuck up. Long shots give the offense an advantage a lot of times on the boards. This is something I disagree fully with the group that we have. I know we're missing our top rebounders but Nunn, Hill, Williams, Jordan, and even Tate are pretty athletic for the guard spots, and I feel we could grab a few extra possessions crashing the boards.
 
#22      
I don't blame Groce for concentrating on getting back over O rebounding with this team. The only RBs we're going to get are the long ones and they're too unpredictable. My first priority for rebounding would be on the defensive end. We must lose 3 out of 4 long rebounds on the D end. Too much watching rather than seeking out guys to box out and guys crashing. And I don't see anyone very good at following the flight of the ball to anticipate where it's going. We have too many possessions where we need a stop, play good D as the clock winds down, force a hurried or bad shot, and then look helpless at corralling the long RBs coming off those shots. JMO.

This and then some....im tired of screaming box out at the tv. We have to be last in B10 for opponents' offensive rebounds.
 
#23      
Ordained Dudeist Priest
Johns Creek, GA
This and then some....im tired of screaming box out at the tv. We have to be last in B10 for opponents' offensive rebounds.

This is correct (by a tremendous margin), at least as far as conference games go, per KenPom. For the season we're #341 (out of 351) in the country. The only power conference team worse than Illinois in offensive rebounding is Boston College.
 
#24      

Deleted member 29907

D
Guest
If our defense wasn't such a turnstyle I could see this strategy making sense, but with the percentage of shots we miss I can't help but think we'd be significantly better off if we at least TRIED to get offensive boards. I can't imagine how many second chance points were are missing out on, not to mention limiting the number of possessions of our opponents.

Yeah - how much of a factor is it that we're already short 3 starters on this team? Quick break opportunities might lend themselves to more (out of position) fouls by our guys - and we're already short handed... same could be true of crashing the boards - more foul potential 90 ft from the rim. I don't know if that in any way plays in to the sprint back on D approach or not...