Post by eric on Jul 21, 2016 13:58:45 GMT -6
NBA rim protection is a really interesting concept to me. stats.nba.com has figures that define it as field goals attempted when the defender is within five feet of the rim and five feet of the opposing player. This is pretty obvious, and although we can see large areas it leaves out (such as fouls drawn and committed, pace, strength of schedule, teammates) it's a valuable starting point because it tells us both how well opponents shoot at the rim against a particular player and how often. This second point gets a little thorny so I am going to elaborate.
Deterrent or Defective?
We don't have any information from the inside of the shooting player's head, so we have no way of knowing if he's thinking "uh oh Excellent Rim Protector is in the lane, I better pull up for a floater instead of challenging him." It is a thought that is very plausible, but if we look at a graph of field goals defensed per 36 minutes versus field goal % allowed, we actually see a very slight trend in the opposite direction:
This is all 119 players with 2000+ MP and 5+ FG per 36 MP for total data over the last three seasons. If elite defense deterred shots, we would see a line going from the bottom left (lowest FG% allowed, least FG per MP) to the upper right (highest, most), but we see the opposite. I want to stress that I'm not suggesting players think "oh, Rudy Gobert? big deal I can take him." Rather, I'm suggesting that being at the rim to defend a shot in the first place is a skill, that it is correlated with the skill of defending a shot, and it outweighs the deterrence effect whether it exists or not.
Okay, so what? So I think we can produce a unified measure of rim protection by saying that every field goal attempt not defensed counts against the player, and does so at a rate of the worst field goal percentage allowed in this sample (60%). This formalism has the result that exactly two players retain their raw percentage: the player who defends the most field goals and the player who has the worst percentage allowed. I think that's pretty reasonable, but let's see the top and bottom ten:
I think these names all pass the eye test (and Orlando should be very excited), which I hope lends credence to the following measurements of names I found interesting:
-It's comical how little rim protection last year's Cavs bigs offered over this sample. Birdman is getting reallllyy old, but if he can give the Cavs 15 minutes a night of above average rim protection I think that'll be a huge boon. He's always been a composite stats darling, I think Cavs fans should be very happy at that pickup.
-Also getting really old is Pau Gasol, and though he has often (and fairly) been derided for his defense, when it comes to defending the rim he's quite good. I feel like the Spurs are an excellent location for him because Pop can definitely scheme around his weaknesses (i.e. moving) and pairing him with Kawhi or LaMarcus at the four would be lethal on offense.
-Snaps and KAT being this high this young is very, very interesting, although of course they have only one season played and so are more prone to small sample size error than others. Still, they are already above average on both sides of this equation: getting into defensive position and holding opponents to low FG% when they do.
-Dwight still holds people to a below average %, but the number of attempts he gets to was low even three years ago and has declined both years since. Three years doesn't seem like a long time, but if his defense continues to slip it could still be a real disaster for Atlanta. His FT% before he hurt his back was 60%, it's been 50% since with no signs of improving.
-Anthony Davis holds people to a good (but not great) percentage, around 75th percentile in this sample. His ability to get to the positions where he can enforce that percentage is the opposite (around 25th percentile), and even more alarmingly it was worse last year than either of the two years previous.
Deterrent or Defective?
We don't have any information from the inside of the shooting player's head, so we have no way of knowing if he's thinking "uh oh Excellent Rim Protector is in the lane, I better pull up for a floater instead of challenging him." It is a thought that is very plausible, but if we look at a graph of field goals defensed per 36 minutes versus field goal % allowed, we actually see a very slight trend in the opposite direction:
This is all 119 players with 2000+ MP and 5+ FG per 36 MP for total data over the last three seasons. If elite defense deterred shots, we would see a line going from the bottom left (lowest FG% allowed, least FG per MP) to the upper right (highest, most), but we see the opposite. I want to stress that I'm not suggesting players think "oh, Rudy Gobert? big deal I can take him." Rather, I'm suggesting that being at the rim to defend a shot in the first place is a skill, that it is correlated with the skill of defending a shot, and it outweighs the deterrence effect whether it exists or not.
Okay, so what? So I think we can produce a unified measure of rim protection by saying that every field goal attempt not defensed counts against the player, and does so at a rate of the worst field goal percentage allowed in this sample (60%). This formalism has the result that exactly two players retain their raw percentage: the player who defends the most field goals and the player who has the worst percentage allowed. I think that's pretty reasonable, but let's see the top and bottom ten:
dFG%+ name
.442 Rudy Gobert
.465 Roy Hibbert
.467 Andrew Bogut
.469 Hassan Whiteside
.472 Robin Lopez
.475 Bismack Biyombo
.478 Serge Ibaka
.478 John Henson
.489 Nerlens Noel
.490 Tim Duncan
.576 Andrea Bargnani
.577 Markieff Morris
.577 Brandon Bass
.578 Nikola Pekovic
.579 Ersan Ilyasova
.580 Boris Diaw
.580 Ryan Anderson
.583 Julius Randle
.591 Luke Babbitt
.592 Thaddeus YoungI think these names all pass the eye test (and Orlando should be very excited), which I hope lends credence to the following measurements of names I found interesting:
dFG%+ rank name
.506 16 Pau Gasol
.512 22 Jonas Valanciunas
.515 24 DeAndre Jordan
.516 26 Kristaps Porzingis
.520 29 Karl-Anthony Towns
.521 31 Dwight Howard
.523 35 Steven Adams
.523 38 Chris Andersen
.529 43 Al Horford
.529 44 DeMarcus Cousins
.536 52 LaMarcus Aldridge
.538 59 Tyson Chandler
.539 60 Anthony Davis
.552 81 Channing Frye
.555 84 David West
.566 96 Tristan Thompson
.568 99 Anderson Varejao
.569 101 Kevin Love-It's comical how little rim protection last year's Cavs bigs offered over this sample. Birdman is getting reallllyy old, but if he can give the Cavs 15 minutes a night of above average rim protection I think that'll be a huge boon. He's always been a composite stats darling, I think Cavs fans should be very happy at that pickup.
-Also getting really old is Pau Gasol, and though he has often (and fairly) been derided for his defense, when it comes to defending the rim he's quite good. I feel like the Spurs are an excellent location for him because Pop can definitely scheme around his weaknesses (i.e. moving) and pairing him with Kawhi or LaMarcus at the four would be lethal on offense.
-Snaps and KAT being this high this young is very, very interesting, although of course they have only one season played and so are more prone to small sample size error than others. Still, they are already above average on both sides of this equation: getting into defensive position and holding opponents to low FG% when they do.
-Dwight still holds people to a below average %, but the number of attempts he gets to was low even three years ago and has declined both years since. Three years doesn't seem like a long time, but if his defense continues to slip it could still be a real disaster for Atlanta. His FT% before he hurt his back was 60%, it's been 50% since with no signs of improving.
-Anthony Davis holds people to a good (but not great) percentage, around 75th percentile in this sample. His ability to get to the positions where he can enforce that percentage is the opposite (around 25th percentile), and even more alarmingly it was worse last year than either of the two years previous.
