Why Do Lefty Batters Hit into Fewer Double Plays?
Photo Credit: AP Photo/Seth Wenig
Over the last 9+ seasons, MLB pitchers have been able to induce about 1.5 double plays per game—0.75 for each team. Double plays enable pitchers to both get out of major jams and keep their pitch counts manageable.
In this analysis, I’ll examine the difference in the propensity to ground into double plays for righty batters and lefty batters and determine what this could mean for in-game strategy.
Of the 6.2 million pitches thrown in the last 9+ seasons, 41.56% have been thrown to lefty batters and 58.44% have been thrown to righty batters. But of the 30,678 GIDPs (grounded into double plays), only 33.55% have been grounded into by lefties and 66.45% have being grounded into by righties. Therefore, lefties ground into an extremely significant 8.01% fewer double plays than one might expect based on the ratio of pitches faced.
Why is this? My initial hypothesis is two-fold:
Lefty batters are closer to first base, so they are able to beat the return throw to first and avoid the double play more often.
73.16% of double plays are grounded into with a runner on first base and no runner on second base. In these situations, the first baseman holds on the runner. The first baseman holding on the runner opens up more room for a lefty batter’s roll-over groundball, which might have otherwise been a double play grounder, to find the hole between the first and second basemen and make it into right field.
I broke the double play data down even further to test the validity of hypothesis number 2, and the results were not at all what I was expecting:
With a runner on first base and no runner on second base, lefty batters ground into 34.72% of double plays. In all other situations, lefty batters ground into only 30.38% of double plays. Having the first basemen hold on the runner is actually increasing the percentage of double plays that lefties ground into by 4.34%!
Does this make sense intuitively? Actually, it does. The first baseman, when playing much nearer to the bag, is able to field the double play groundball, step on first base, and fire to second base for a tag play to finish the double play. The ability to make that play when playing closer to the bag more than offsets the groundballs to his right that are not turned into double plays.
What Does This Mean for Defensive Strategy?
Teams should elect to have the first baseman hold on the runner at first base when lefty batters are batting in double play situations. This will not only increase their chances of turning a double play, but also reduce the chance the runner on first scores this at-bat, since the first baseman is also able to guard the line when playing closer to “no doubles” defense.
