Zach Lowe notes that the Memphis Grizzlies employed a peculiar-sounding strategy in their Game 1 victory over the San Antonio Spurs.
The Grizzlies fouled so often in Game 1, sending the Spurs to the line 47 times, that some experts wondered if perhaps they did so on purpose as a way of halting San Antonio’s dribble penetration before something really bad happened. In other words: Two free throws are better than a wide-open corner three.
Something that on the surface may seem counter-intuitive – why purposely send a player to the free throw line? – actually makes a world of sense when viewed through a basic application of expected value.
Used often in poker and the financial sector, expected value is simply a way of determining the average result of a probability-based situation. By defining specific parameters, we can effectively calculate which of two or more options is the most profitable – or in basketball terms, which action creates the most points on average.
If Tony Parker, for example, is handling the ball for the Spurs and forces the defense to collapse on his penetration into the lane, we can readily figure out the value of fouling him and giving him two free throws. As a 77% free throw shooter, each one is worth .77 points; two free throws, then, are worth 1.54 points.*
*For the sake of simplicity (and due to lack of data), we’ll be ignoring the impact of offensive rebounding and assume that the offensive rebound rate on misses is equal across shots. This is almost certainly not the case, depending on where an offensive set leaves potential rebounders versus the static rebounding formation on a free throw. For ease of explanation, though, we’ll skip that.
The other option in this scenario is an open corner 3 for Matt Bonner or Gary Neal. According to the invaluable StatsCube on NBA.com, Bonner shoots 41%, on average, from the corner; Neal shoots 43%. Multiplying those rates times the value of a made 3 produces an expected value of 1.23 points for a Bonner 3 and 1.29 for Neal.
But wait, we’re not dealing with the average corner shot – Lowe mentioned wide open shots specifically. A recent episode of ESPN’s SportsScience referenced the fact that an open shot is 12% more likely to go in than one tightly defended. If either player makes 51.4% of their corner 3s or more, than the value of that shot (greater than or equal to 1.542) is more than sending Parker to the line.
In Game 1, there was no difference between the two propositions. Parker shot 75% from the free throw line, giving two free throws an expected value of 1.5 points. Bonner and Neal went 4-for-8 from deep – also an expected value of 1.5 points.
Unfortunately, I don’t have access to the larger sample size of Bonner and Neal’s accuracy when open in the regular season – but you can be certain that the Memphis Grizzlies (and all other NBA teams) track exactly that and hundreds of other bits of data. If the Grizzlies are fouling the Spurs so aggressively, you can be sure they’re doing it with the knowledge that Tony Parker on the line is less destructive than Matt Bonner raining sandwich-laced bombs all over your dome-piece.