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NBA players are fouling out less often and other interesting facts you didn’t think you wanted to know about fouling out

In his Wednesday Bullets, TrueHoop’s Henry Abbott posed a question:

Help me out, if you can: Do players foul out less than they used to? Seems like it used to happen all the time. Now it seems so rare. I can’t tell if that’s really a trend, or just an artifact of a childhood watching Steve Johnson, king of six fouls.

I wish I could’ve just ignored that, but I couldn’t. My curiosity wouldn’t let me.

So, after a considerable amount of time with Basketball-Reference’s Game Finder, I have some answers.

In short, players do foul out less than they used to. In long,* well, let me guide you through some of my findings.

*Why is that phrase not used? Is there any way to make it catch on?

Methodology

Basketball-Reference’s Game Finder dates back only to the 1986-87 season, so that’s as far as my data goes.

The charts I use refers to each season by a single year. For example, this season is 2011.

Because of expansion, the lockout-shorted season of 1999 and this year being only about a quarter through, I use foul outs per game, rather than foul outs per season. That way, each season is on a level playing field.

Fouling out headed out of style

Between the beginning of the 1986-87 season and Tuesday, 1,144 different players fouled out 11,197 times. But those numbers are hardly evenly distributed over the past 25 years.

Henry was right. Foul outs per game are down 43.3 percent from 1986-87 to this season. And players are fouling out more this season than any of the last three seasons!

The solid blue line represents the actual year-to-year figures for foul outs per game. The dotted red line represents a linear trend line for that data.


Why is this happening?

As a believer in Occam’s Razor, I wanted to start with the simplest explanation. In this case, I wanted to know whether players are fouling less. If they are, that would explain why players are fouling out less.

Again, I use fouls per game, rather than fouls per season, because of expansion, the lockout-shorted season of 1999 and this year being only about a quarter through, 

The solid blue line represents the actual year-to-year figures for foul per game. The dotted red line represents a linear trend line for that data.


This makes sense. Fouls decreasing through the years probably has something to with players fouling out decreasing.

But why players are fouling less?

My first, and really only guess, was pace. If the pace of the league has decreased over the last 25 years, there would be fewer possessions, and therefore fewer fouls.

The solid blue line represents the actual league-wide pace. The dotted red line represents a linear trend line for that data.


Again, this makes sense. Fewer possessions, fewer fouls, fewer foul outs. I’m sure fewer fouls has something to do with fewer players fouling out. But that’s not the whole story.

As I said above, foul outs per game have declined 43.3 percent in the last 25 years.

In that same span, the league’s pace has declined a mere 8.7 percent, and fouls per game have declined just 11.8 percent.

To illustrate this, I created foul outs per game plus, fouls per game plus and pace plus. I set the average foul outs per game, fouls per game and pace for the last 25 years each at 100. Then, I adjusted each season’s value for all three measures accordingly.*

*This model is similar to OPS-plus and ERA-plus for baseball.

Foul outs per game plus is in gray. Fouls per game plus is in red. Pace plus is in blue. Solid lines are actual numbers, and dotted lines are the linear trend lines.


The rate of decline for fouls per game and pace are pretty well in tune. In fact, I believe the decline in fouls per game is almost directly tied to pace.

But what about foul outs per game? They’ve declined significantly more rapidly than fouls and pace.

Why?

Conspiracy!

Let me preface this section by saying I don’t believe there’s a conspiracy to reduce the number of times players foul out. But with anything in the NBA that doesn’t quite stack up, isn’t there an obligation to invent a conspiracy?

As you can tell by the above chart, although fouls outs were trending downward, they really have sunk since 2007. What happened that year? The Spurs beat the Cavaliers in the Finals:

Stern and network executives downplayed the league’s declining TV ratings, insisting there is still plenty of demand for NBA-related content through other forms of media.

San Antonio’s recent four-game sweep of Cleveland finished with a record-low 6.2 television rating and 11 share on ABC.

Could the NBA have instructed referees to try to prevent players from fouling out to improve television ratings? After all, fewer people will watch games if star players are stuck on the bench.

The reason I don’t buy that theory – besides the biggest reason: conspiracies are difficult to pull off because few people can keep a secret – is although Finals rating were down, playoff ratings were trending upward. The low Finals rating were more likely due to an unpopular matchup than a larger problem with the NBA.

And Drew Gooden was the only player to foul out during the Finals. The lower ratings certainly can’t be blamed on that. So, I doubt the NBA saw any cause to scheme about preventing players from fouling out.

The real reason

Part of the reason I offered the conspiracy theory was because I’m low on more realistic ideas. I wish I had something of substance to write here, but I just don’t know.

One thought: players are playing fewer minutes per game now than before and are therefore less likely to get into serious foul trouble. But glancing at last season and 1986-87, that wasn’t the case.

The only guess I have left: I think coaches too often sit players who are in minor foul trouble early. Obviously, that makes the player less likely to foul out. But I don’t think the lost playing time is worth minimizing the risk of fouling out. Has this strategy grown favor during the last 25 years?

I’d love to hear suggestions about what’s causing this trend.

In the mean time, as long as I had all this data in front of me, here are some more foul-out facts.

By position

Here’s a breakdown of the percentage of players at each position who fouled out in the last 25 years:


Fouling-out superlatives

In games players fouled out, they averaged 12.3 points, 5.9 rebounds, 2.2 assists, 0.9 steals and 0.8 blocks in 29.3 minutes. Here are the extremes:

Leaders since 1986-87

Here are the 25 players who’ve fouled out the most the last 25 years. Shawn Kemp might be solely responsible for slowing the decline of players fouling out.


For the record, Steve Johnson fouled out 25 times since 1986-87. But he only played half his 10 seasons since then. I have no record of how many times he fouled out his first five years.

Annual leaders

Johnson makes an appearance in the final chart, which displays the leader(s) in fouling out each of the last 25 years:


13 Comments

  • Dec 9, 201011:04 am
    by Glenn

    Reply

    Great article Dan.  Rather than commenting on all your stats, I’ll comment on your asterisk.  I think that the reciprocal phrase for “in short”  could maybe be “at length?”  Just a thought.

  • Dec 9, 201011:29 am
    by EddieM

    Reply

    What about taking into account the wisdom of committing fouls?  A well-placed foul (and sometimes a hard one) is an important tool for a defender, as long as the cost of committing a foul is less on average than the cost of not committing one in the same situation.  The potential to foul out is only one disincentive:  if there were not other disincentives it would make sense for all players to try to average 5 judicious fouls per game–and in trying, more players would go over the top and foul out more often. 

    The other disincentive is free throw opportunities for the player fouled.  So it makes sense to ask whether, over the years, the trends toward less fouls and less fouling out correlate with a trend toward better free throw shooting percentages (ie, when I know I’m defending a poor free throw shooter, I’ll foul more often, and vice versa).

    Finally, I would also be interested in an analysis that takes into accout rule changes over the years regarding the limits on non-shooting fouls before a team is in the bonus.  That is, if it takes 8 fouls per quarter before a team earns the right to shoot free throws on non-shooting fouls, then I have more opportunities for judicious use of my personal allotment of 5 fouls per game (and thus more incentive to push the limit of 6 and foul out more often) than if it takes 6 fouls per quarter to reach the bonus.  Have these rules changed over the years represented by your analysis? (Sorry I haven’t kept track of this; I’m old enough to remember when a shooting foul in the bonus resulted in three-to-make-two, and a non-shooting foul resulted in one-and-one.  There’ve been enough changes over the years that I have a hard time keeping up.)

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  • Dec 9, 201012:04 pm
    by Kyle W

    Reply

    I would suggest also tracking the number of 5-foul games over the same data set, and seeing if that number is more stable than the number of 6-foul games. If it is, then it nudges the conversation slightly more toward referees not fouling players out, since the common complaint about coaches sitting players with 2 fouls in the 1st or 3 in the 2nd is that they finish with 2 or 3 fouls.

  • Dec 9, 20101:20 pm
    by nuetes

    Reply

    Congrats on writing such a great article. This is quite possibly the most interesting read PP has provided, and that’s no insult, that’s pure adulation.
     
    I might add something about the flagrant foul (1 and 2) rule and the clear path foul that would explain something. Of course I’m not sure when those rules were adopted by the NBA. It seems fouls were not only more frequent back in the day, but also more ferocious. But that could be explained in the pace v. fouls correlation I would imagine. I still think they played a big effect in players not fouling at as frequently, and countered by the hand check rule that draws more fouls these days. No data in front of me but I would assume there are more fouls taking place outside of the paint than there used to be, and fewer fouls inside the paint because of the flagrant fouls rule and the hand check rule.
     
    Another theory. Expansion. Rosters are stretched thinner these days due to expansion, and the gap between a top player and a bench player has grown. Back in the day fouling out wasn’t as bad of a thing for a team because team’s were stacked with better overall talent from top to bottom because there were fewer teams in the league. Again just a theory and trying to throw out something.

  • Dec 9, 20101:48 pm
    by nuetes

    Reply

    Ok back to strengthen my argument. I don’t think I made it that clear but the data shows that fouls have have decreased on par with pace so we have to find a reason why players aren’t fouling out as much, despite still fouling as much. My argument boils down to the distribution of fouls. Because of the flagrant rule and the hand check rule the distribution of fouls is more evenly placed between guards and forwards. It also shows that of the players fouling out only 22.8% of those were guards. So the majority of foul outs come from forwards and centers. So my guess is that fouls are more evenly distributed now, and because of the flagrant rule big men are more conscious of committing fouls on the interior while the hand check rule is causing guards to commit more fouls away from the basket.
     
    I found a real interesting sheet from the NBA that would aid any speculation in this phenomenon. It’s the NBA rule change history.
     
    http://www.nba.com/analysis/rules_history.html
     
     

  • Dec 9, 20108:31 pm
    by Stephen

    Reply

    Partially explainable by big men moving outside.
    W/Cs and PF shooting ouside  there’s less contact inside,less help fouls,less fighting for position. Howard is the only C who shoots a lot of FTs.
    Another possible explanation is minutes played. Off eyeball memory,players used to play 40+ minutes a game. Now it’s rare someone averages over 36 minutes. If I’m right,fouls would be spread among more bench player minutes,lessening the chance of starter fouling out.
    Finally,it’s common to hear game commentators say a star player has 5 fouls and will not get a 6th w/out killing someone. Be interesting to see game minutes between 1 and 2nd and then 3rd foul and so on.
    OTOH,didn’t Wilt go seasons on end w/out fouling out of a game?

  • [...] Has fouling out gone out of style? Or are coaches protecting their players [...]

  • [...] Pistons blogger ran the stats and found that Shawn Kemp fouled out the most of any NBA player over the last 25 years. By a [...]

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    Dec 10, 201012:14 pm
    by Field Trip Friday // 005 |

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    [...] -NBA players are fouling out less and less, and Dan Feldman does the dirty work over at Piston Powered. [...]

  • Dec 10, 20108:54 pm
    by Tom

    Reply

    The explanation to first order is simple:  it takes 6 fouls to be ejected, fouls have declined at 11.8% = 0.882 probability of picking up a foul, raise that to the 6th power to get probability of fouling out = 0.47, then take 1 minus it to get the decrease in probability of fouling out = 0.53 = 53%.  That is reasonably close to the probability you quote.  If you look at the curves for fouls per game and foul outs they are highly correlated.  This would also lead us to come to the conclusion that most of it can be explained solely by the decrease in the rate of fouls.

  • [...] Feldman, D. (2010). NBA Players are Fouling Out Less Often. Detroit: PistonPowered.com. Accessed at: http://www.pistonpowered.com/2010/12/nba-players-are-fouling-out-less-often-and-other-interesting-fa… [...]

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