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April 29, 2010

The Foul Factor

Filed under: Uncategorized — Kevin Pelton @ 1:06 pm

Yesterday, John Hollinger had one of the most interesting takes on the playoffs thus far when he studied how the Denver Nuggets’ foul rate has changed since Adrian Dantley replaced George Karl on the sidelines (Insider only).

Given the eye-popping differentials in foul calls and free throw attempts, we have to ask if human nature has made some officials respond different to Dantley than to a more intimidating, permanent coach like Jerry Sloan. Are the refs more likely to call, say, three charging fouls in a half on a team’s superstar, or call a delay-of-game violation for a technical foul with three minutes left in a close playoff game, or make a dramatic zip-your-lips gesture to the bench as if lecturing a room full of third-graders if the person reacting to that call is basically the substitute teacher?

They’re the best officials in the world. But they’re only human, after all.

I was compelled to look into the numbers a bit more, focusing on Denver’s free throw attempts per game. If my math is right (and comparing two samples is a little tricky from a statistical standpoint), the difference between the Nuggets’ 31.6 attempts per night under Karl and 27.1 with Dantley during the regular season is statistically significant.

The fact that Denver played more road games than home (11 out of 19) with Dantley does mitigate that a little bit. I ran a regression attempting to relate the Nuggets’ free throw attempts to game location, pace and opponents’ tendency to put teams on the free throw line, adding the coach as a dummy variable. With this adjustment, Dantley’s impact on the team’s free throw attempts per night drops slightly to 3.1 per game and is no longer quite statistically significant. Still, the magnitude of the effect is considerable.

Now, the main reaction to Hollinger’s piece has been commentary on the fact that free throw attempts evened out in the Denver-Utah series last night, with the Nuggets getting to the charity stripe 42 times to the Jazz’s 25 in their Game Five win. That stat can’t be considered in a vacuum; Denver was playing at home, was desperate to extend the series and played much more energetic basketball than in its three straight losses. Still, to the extent the Nuggets haven’t been getting calls under Dantley, that certainly wasn’t the case last night, and the situation being made public may well have had something to do with that. In fact, Hollinger predicted as much.

What strikes me is whether we can quantify how other coaches affect the way their teams are refereed. This would be tricky, for any number of reasons–predicting fouls from the stats is challenging, and disentangling players’ existing foul rates from the effect of coaches when most of them tend to work together for multiple seasons is tough–but surely this can’t be the only case where a coach makes a difference at the free throw line. One I investigated in the WNBA was whether the imposing Bill Laimbeer helped his team by intimidating referees (and whether this effect wore off over time). Such a study is probably beyond my statistical capabilities, and I don’t like making work for other people, but I’d love to see one done.

Kevin Pelton is an author of Basketball Prospectus. You can contact Kevin by clicking here or click here to see Kevin’s articles. Follow Kevin on Twitter at @kpelton.

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