scott
07-06-2024, 12:34 PM
I wanted to make this post because I see a lot of misusage (heh) of the USG% stat in rhetorical arguments. A fine example:
Yeah that player's scoring average went up, but it's only because their USG% went up. Once their USG% goes down, so will their average. We shouldn't want that player.
This statement sounds like someone who has some deep understanding of advanced stats and has uncovered some unique and meaningful insight into a player's game, when in reality they're just telling you what would be an obvious relationship between a basic counting stat (points per game) and an advanced stat (USG%).
What does USG% tell us? Basketball-reference.com and NBA.com use slightly different formulas to calculate USG% (which you can find here (https://www.basketball-reference.com/about/glossary.html#:~:text=Usg%25%20%2D%20Usage%20Perce ntage%20(available,he%20was%20on%20the%20floor.) and here (https://www.nba.com/stats/help/glossary#usgpct)), which spit out slightly different results, but they are both telling you the same thing: the percentage of a team's plays that end with an individual player while he is on the court. A play can only end in a finite number of ways: a made shot, a missed shot, or a turnover. That's it. There is no other way for a play to end except for the game clock expiring, which counts as nothing. There is no other possible way for a play to end.
USG% does not measure: how ball dominant a player is, or how much they need the ball in their hands, or how much of a possession a player takes up, or whether they set up their teammates, etc. It only tells us the percentage of a team's plays that end with an individual player while he is on the court.
A very exaggerated example of how USG% can be deceiving:
Imagine a game of 2-on-2 with a 24 second shot clock and 100 plays per team and every shot is worth 2pts.
Player A and Player B are teammates. Player A brings the ball down the court and on EVERY possession, dribbles the ball around the court for 23 seconds before passing it to Player B, who is forced to throw up a quick shot or get caught with the ball in his hands as the shot clock expires (a turnover). Let's say that 50% of the time he gets the shot off, and 20% of the time he makes it. The other 50% of the time he commits a turnover. Let's also assume every missed shot ends in a defensive rebound.
In this scenario, Player A will have a USG% of 0, and Player B will have a USG% of 100. Player A will average 10 assists/gm, Player B will average 20 ppg on 20% shooting and 50 TOV/gm.
This is a purposely exaggerated example to show you that USG% isn't really all that insightful at all. You might look at the stats and conclude that Player B is a ball dominant, inefficient chucker who is sloppy with the ball, when that's not really the case at all.
I'll come back to this example a little later.
Because scoring is the result of shooting the basketball, there is an extremely strong correlation between USG% and scoring average. So strong, in fact, that among the Top 40 scorers in the NBA last year, 36 of them were in the Top 40 in USG%.
Here is a scatter plot of the PPG average of the Top 40 scorers last year against their USG%.
https://i.ibb.co/cNNVLjp/USG-v-PPG.png
You'll notice a pretty clear correlation here, which makes sense. To score, you must shoot, and by shooting more, your USG% increases. Pretty straightforward, right?
There is a wrinkle, of course - and that is in a player's TOV rate and their shooting efficiency.
If we go back to our exaggerated example, if Player B increases his shooting % from 20% to 30% (remember, these are all tough shots he's taking, thanks to his teammate), then his scoring average will increase from 20ppg to 30ppg while his USG% will remain unchanged. Similarly, if he maintains his shooting % of 20%, but he reduces his turnovers from 50/gm to 40/gm, and those 10 possessions generate 10 extra shots, his scoring average will increase from 20ppg to 24ppg.
So, whenever we see a player's PPG increase, then there can only be a handful of explanations why: his USG% went up, his shooting efficiency went up, or his turnovers were replaced with more shots (if his turnovers are reduced but they are not replaced by shots, then his USG% will just go down without a corresponding increase in PPG).
So, whenever you see someone say this:
HiS sCoRiNg WeNt Up OnLy BeCaUsE hIs UsG% WeNt Up
You can respond with "yeah, no shit."
The idea that the Spurs will add a #2 scorer whom they'll presumably pay the max at some point, and then turn around and reduce their usage considerably is a weird concept. Why would you acquire that player just to do that? Likelywise, if that player is more efficient at scoring, why would you want to reduce their usage for someone who is less efficient? The only explanation would be that you expect that player's efficiency to increase dramatically. This would be the situation with Wemby. He's actually one of the less efficient high usage scorers, ranking 39th in scoring average but #8 in USG%. But he was a rookie, and we expect that to continue to improve dramatically as his shooting improves and (maybe more importantly) his turnovers are reduced.
Coincidently, among the Top 40 scoring average leaders last year, two of the two most efficient were Demar Derozan, who ranked #24 in scoring but #44 in USG%, and Lauri Markkanen, who ranked #26 in scoring but #51 in USG%. In the case of Lauri, that's because he's a highly efficient scorer (indeed, he's a 50/40/90 guy who doesn't commit a lot of turnovers). So it's odd to hear people say they'd want him to be our number 3 option, or his usage would get significantly reduced if we signed him... why would you do that? Why would you prefer less efficient Devin Vassell shots or Keldon Johnson shots to highly efficient Lauri Markkanen shots?
Yes, this has been a secret Lauri post. But hopefully you learned something in the meantime, and folks can cut back on their utterly braindead misusage (heh) of USG%.
Yeah that player's scoring average went up, but it's only because their USG% went up. Once their USG% goes down, so will their average. We shouldn't want that player.
This statement sounds like someone who has some deep understanding of advanced stats and has uncovered some unique and meaningful insight into a player's game, when in reality they're just telling you what would be an obvious relationship between a basic counting stat (points per game) and an advanced stat (USG%).
What does USG% tell us? Basketball-reference.com and NBA.com use slightly different formulas to calculate USG% (which you can find here (https://www.basketball-reference.com/about/glossary.html#:~:text=Usg%25%20%2D%20Usage%20Perce ntage%20(available,he%20was%20on%20the%20floor.) and here (https://www.nba.com/stats/help/glossary#usgpct)), which spit out slightly different results, but they are both telling you the same thing: the percentage of a team's plays that end with an individual player while he is on the court. A play can only end in a finite number of ways: a made shot, a missed shot, or a turnover. That's it. There is no other way for a play to end except for the game clock expiring, which counts as nothing. There is no other possible way for a play to end.
USG% does not measure: how ball dominant a player is, or how much they need the ball in their hands, or how much of a possession a player takes up, or whether they set up their teammates, etc. It only tells us the percentage of a team's plays that end with an individual player while he is on the court.
A very exaggerated example of how USG% can be deceiving:
Imagine a game of 2-on-2 with a 24 second shot clock and 100 plays per team and every shot is worth 2pts.
Player A and Player B are teammates. Player A brings the ball down the court and on EVERY possession, dribbles the ball around the court for 23 seconds before passing it to Player B, who is forced to throw up a quick shot or get caught with the ball in his hands as the shot clock expires (a turnover). Let's say that 50% of the time he gets the shot off, and 20% of the time he makes it. The other 50% of the time he commits a turnover. Let's also assume every missed shot ends in a defensive rebound.
In this scenario, Player A will have a USG% of 0, and Player B will have a USG% of 100. Player A will average 10 assists/gm, Player B will average 20 ppg on 20% shooting and 50 TOV/gm.
This is a purposely exaggerated example to show you that USG% isn't really all that insightful at all. You might look at the stats and conclude that Player B is a ball dominant, inefficient chucker who is sloppy with the ball, when that's not really the case at all.
I'll come back to this example a little later.
Because scoring is the result of shooting the basketball, there is an extremely strong correlation between USG% and scoring average. So strong, in fact, that among the Top 40 scorers in the NBA last year, 36 of them were in the Top 40 in USG%.
Here is a scatter plot of the PPG average of the Top 40 scorers last year against their USG%.
https://i.ibb.co/cNNVLjp/USG-v-PPG.png
You'll notice a pretty clear correlation here, which makes sense. To score, you must shoot, and by shooting more, your USG% increases. Pretty straightforward, right?
There is a wrinkle, of course - and that is in a player's TOV rate and their shooting efficiency.
If we go back to our exaggerated example, if Player B increases his shooting % from 20% to 30% (remember, these are all tough shots he's taking, thanks to his teammate), then his scoring average will increase from 20ppg to 30ppg while his USG% will remain unchanged. Similarly, if he maintains his shooting % of 20%, but he reduces his turnovers from 50/gm to 40/gm, and those 10 possessions generate 10 extra shots, his scoring average will increase from 20ppg to 24ppg.
So, whenever we see a player's PPG increase, then there can only be a handful of explanations why: his USG% went up, his shooting efficiency went up, or his turnovers were replaced with more shots (if his turnovers are reduced but they are not replaced by shots, then his USG% will just go down without a corresponding increase in PPG).
So, whenever you see someone say this:
HiS sCoRiNg WeNt Up OnLy BeCaUsE hIs UsG% WeNt Up
You can respond with "yeah, no shit."
The idea that the Spurs will add a #2 scorer whom they'll presumably pay the max at some point, and then turn around and reduce their usage considerably is a weird concept. Why would you acquire that player just to do that? Likelywise, if that player is more efficient at scoring, why would you want to reduce their usage for someone who is less efficient? The only explanation would be that you expect that player's efficiency to increase dramatically. This would be the situation with Wemby. He's actually one of the less efficient high usage scorers, ranking 39th in scoring average but #8 in USG%. But he was a rookie, and we expect that to continue to improve dramatically as his shooting improves and (maybe more importantly) his turnovers are reduced.
Coincidently, among the Top 40 scoring average leaders last year, two of the two most efficient were Demar Derozan, who ranked #24 in scoring but #44 in USG%, and Lauri Markkanen, who ranked #26 in scoring but #51 in USG%. In the case of Lauri, that's because he's a highly efficient scorer (indeed, he's a 50/40/90 guy who doesn't commit a lot of turnovers). So it's odd to hear people say they'd want him to be our number 3 option, or his usage would get significantly reduced if we signed him... why would you do that? Why would you prefer less efficient Devin Vassell shots or Keldon Johnson shots to highly efficient Lauri Markkanen shots?
Yes, this has been a secret Lauri post. But hopefully you learned something in the meantime, and folks can cut back on their utterly braindead misusage (heh) of USG%.