Revisiting the Upper Limits of Shifting

Last March, Baseball Info Solutions devoted a Stat of the Week article to determining the upper limits of defensive shifts. Today we’re going to revisit that analysis.

This offseason, BIS made modifications to their shifting software BIS-D. The software used to recommend shifting left-handed hitters who pull grounders and short liners at least 80 percent of the time and right-handed hitters who pull at least 85 percent. However, recent research indicated defensive shifting was effective on even less pull-heavy hitters, and thus, these thresholds were decreased to 75 percent for lefties and 80 percent for righties.

So how does this adjustment impact the potential bounds on shifting across Major League Baseball? Here is a quick look into how shifting has trended over the last six seasons.

In 2015, BIS-D recommended deploying a full Ted Williams shift—three infielders on the strong side of second base—on 221 hitters. This number was up from 113 recommended shift candidates in 2014, which was based off the old pull-rate parameters. That five percent change for both lefties and righties really swings the needle as the recommended number of candidates nearly doubled from 2014 to 2015.

The 221 shift candidates put more than 50,000 balls in play in 2015, yet only saw 13,683 total shifts. If teams deployed BIS’ full-shift alignment on every recommended shift candidate, the bounds on full shifts last season would’ve been around the 50,000 mark. In aggregate teams still have a long way to go before even flirting with the potential limits of defensive shifts.