Ordinary average bunts

Runner on first, no outs. The table is set for a mistake.

Managers often see this situation as a great opportunity to bunt the runner over, but the numbers show they’re giving away runs and wins even when the sacrifice is executed perfectly.

By giving up an out for a base, teams lose more than they gain. Everyday, run-of-the-mill bunts cost teams in expected run scoring and the probability that they will win.

The most common bunt can be the most damaging type of sacrifice over the long run. The median win probability added of all 2,114 sacrifice bunt attempts in 2013 was -0.02, according to an analysis of data from the Baseball-Reference.com Play Index. That means teams’ odds of winning drops by 2 percentage points when they lay down a bunt.

  • The Cardinals and Diamondbacks were tied at 9 in the top of the 13th inning on April 3, 2013, when Matt Carpenter bunted over Jon Jay to second. The Cardinals went from having a runner on first with no outs to having a runner on second with one out, and their win probability declined by -0.02. Jay never scored, and the Cardinals lost 10-9.
  • With runners on first and second, no outs and trailing 5-3 on April 15, 2013, Luis Cruz of the Dodgers bunted the runners over and was thrown out at first. The Dodgers WPA dipped -0.02, and the Padres went on to win, 6-3.
  • Denard Span bunted over two Nationals’ players to second and third in an effort to come back from a 4-2 deficit. Again, the bunt was successful, but the Nationals lost -0.02 in WPA and lost to the Cardinals 4-3 on Sept. 23, 2013.

If these examples seem similar, that’s because they are.

The same story repeats itself over and over. Each time, teams lose fractions of a win when they bunt runners over.

Bunts may be worthwhile when the pitcher is batting or when a position player is fast enough to bunt for a hit.

But in most other situations, teams shouldn’t bother with the bunt. They’re killing themselves with smallball.