All Your Basketball Are Belong To Us

[RickJay]

Watching tonight's Raptors-Hawks game, I was intrigued by a question; why do NBA players sometimes decide to launch 3-point shots, and why do they then sometimes decide not to try them, even when they have open shots? If it's a good gamble on this possession, why not on the next?

Then just for the hell of it I looked up the NBA's leader in three-point-shot percentage:

1. Stockton, Utah, .491
2. Ferry, San Antonio, .475
3. Barry, Seattle, .470
4. Williams, Seattle, .457
5. Davis, Washington, .455

And so on. 25 NBA players who have taken at least 100 3-point shots hit them 40% of the time.

So now here's my real question; if you have a player who shoots 40% from behind the arc, why don't you just have him take that shot on every possession? Shooting 40% from the arc is the equivalent of shooting 60% from two-point range. NO NBA player shoots 60% inside the arc; it's nearly impossible. If your team shot 60% you'd win pretty much every game - the NBA average is about 43, and a game over 50 is phenomenal. But it seems to me that a guy who shoots 40% when he's getting 50% more points per shot is the equivalent of a guy shooting 60% from two-point range. So if John Stockton or Ray Allen is on the team, why aren't they having them take every available shot from 20 feet? If they continue to shoot 40% or better, isn't that sort of an unbeatable strategy?

[BobT]

Once the defense realizes that a team is only going to shoot 3 pointers, it will bring its defense out to guard everybody out there and the shooting percentages will drop precipitiously.

Also, if everyone is out beyond the three-point line, you will likely get zero offensive rebounds.

Loyola Marymount when it was coached by Paul Westhead and had Bo Kimble and Hank Gathers shot a lot of 3s, but they were only able to score a lot of 3s because Kimble was able to get open because Gathers was able to draw the defenders to him near the basket.

If an NBA team tried an all 3-point attack, it would probably be even less successful than it was in college. The defenses are too good to allow that. Nobody would ever have an open look at the basket if you didn't have to guard anyone in the low post.

[JeffB]

In addition to what BobT said, one reason these players have such high 3-point percentages is that they take 3-point shots that they are more likely to make. If they started to take 3-point shots on every possession, their percentages would drop precipitously.

[scratch1300]

There's a related question, "Why aren't more three-point attempts made when there's only a few seconds left in the game?" According to economist Richard Thaler (in this fascinating article (http://www.nytimes.com/library/magazine/home/20010211mag-econ.html) in the New York Times):

"Thaler studied
games in which a team trails by 2 points, with time left for just one shot.
What to go for, 2 points or 3? A 2-point shot succeeds about half the
time, a 3-pointer about 33 percent of the time. But since a 2-point basket
would only tie the game (and force an overtime, in which the team has a
50-50 chance of winning), going for a 3-pointer is a superior strategy.
Still, most coaches go for 2. Why? Because it lowers the risk of sudden
loss. Coaches, like the rest of us, do more to avoid losing than they do to
win."