Posted by Neil Paine on June 29, 2010
There's a good discussion brewing in the comments of yesterday's thread, centering on whether the big disparity in FTA between L.A. and Boston during the NBA Finals was something we could have expected based on the two teams' season-long tendencies. Here are the facts we know right now:
- Los Angeles received far more free throw attempts per shot in the immediate basket area than Boston did.
- Per possession, Boston was the 3rd-most foul-prone team in the NBA during the season; L.A. was the 2nd-least foul-prone team.
Basically, Boston fouled a lot more than L.A. during the Finals, but they also fouled a lot against everybody, and L.A. was a team that didn't foul much at all. The question is whether the disparity during the Finals was bigger than we would expect based on the teams' known fouling tendencies. Fortunately, I can estimate a team's expected fouls per possession and free throw attempts per possession by comparing their regular-season rates to the league-average and multiplying by their opponent's regular-season rates:
BOS Expected PF/Poss = ((BOS PF/Poss) / (Lg Avg PF/Poss)) * (LAL Opponent PF/Poss)
Boston committed .240 PF/Poss during the regular-season in a league where the average was .223; the Lakers' opponents committed .227 PF/Poss. Therefore, we would expect Boston to commit (.240 / .223) * .227 = .244 PF/Poss against Los Angeles, and in reality they committed .291 PF/Poss... But before you get conspiratorial, consider that the Lakers, who could have expected to commit .219 PF/Poss vs. Boston, actually committed .261 PF/Poss -- so the officials actually called more fouls on everyone. If you scale those numbers back down from the Finals-wide average of .276 to the regular-season league average of .223, the numbers would be .236 for Boston and .211 for L.A., which are actually very much in keeping with the .244 and .219 figures we would expect from their regular-season numbers.
That's only half the story, though -- free throws are where the conspiracy buffs really make their case, since the Lakers shot 51 more FTA than the Celtics did despite Boston taking more shots in the immediate basket area. Using the same methodology outlined above, except with FTA/Poss instead of PF/Poss, we see that Los Angeles took .259 FTA/Poss in a league where average was .263. Boston conceded .285 opponent FTA/Poss during the season, so we would expect L.A. to take (.259 / .263) * .285 = .281 FTA/poss in a series with the Celts; instead, they took .335 FTA/poss. On the other side, we would have expected Boston to have .244 FTA/poss against the Lakers, and in reality they had .249.
This result is unexpected -- Boston essentially had just as many FTA/poss as we would have expected based on team tendencies, but Los Angeles' rate of FTA/poss is dramatically higher than we would have expected. However, neither team's rate of fouls per possession was unexpected, so the only real unexpected outcome of the Finals in the fouling department was the number of free throws Los Angeles shot per foul drawn.