You hear this from casual fans all the time: NBA players only play hard on defense in the fourth quarter, then in the playoffs. As a die-hard NBA fan you can try to refute that all you want — the fact is that even when well defended a lot of NBA players can shoot a reasonable percentage anyway, the “good offense beats good defense” theory — but the more you deny it the more the casual fan wants to believe it.
And statistics show it may be true.
Over at numberfire.com Bryan Mears used the stats from the fantastic NBASavant.com, which digests the NBA’s Sports VU Camera data, and found this:
The average defender is a lot closer to the shooter in the fourth quarter and overtime than in the first three quarters of the game.
In the first quarter the average defender is 4.518 feet away from the shooter, then that number drops slightly in the second and third quarters (4.461 and 4.455 feet). You can understand that drop as teams adjust their defenses and get in the flow of the game.
Then in the fourth quarter that distance drops noticeably to 4.366, then it plummets to 4.063 in overtime. The pattern is more noticeable with shots inside eight feet — the distance is 5.215 in the first quarter and it is 5.002 in the fourth quarter and 4.631 in overtime.
Mears talks about the potential reasons for the drop.
The dip when the fourth quarter hits is the interesting part — it may not seem like much, but considering we’re analyzing thousands of shots that were taken a different distances, a minor change in average defender distance warrants notice.
When overtime comes, things ramp up even more. The league has defined an open shot as one where the defender was four feet away or farther. The average jumpshot is considered uncontested by this definition, but with thousands of open shots and dunks and layups, this is also fairly intuitive. So when that defender distance dips almost to four — like it does it overtime — and the average shot is contested, players are really scrambling and sticking with players.
There are other variables — teams tend to play their better defenders more late, for example. There’s also questions about what this all really means.
To me, the most interesting test would be to run this study again on playoff games. Granted, the best defensive teams generally make and advance farther in the playoffs, but do you see more effort and more contested shots in the postseason than you do generally.
The answer may well be yes.