How Baserunners Alter the Way Teams Shift

As defensive shifts continue to increase across baseball, more and more teams are reaping the benefits of improved run prevention. But how do baserunners affect the way teams shift?

Whether it’s driven by holding runners on, playing at double-play depth, or other situational alignments, teams in aggregate shift less often with more runners on. In the table below, shift percentage represents how often a shift was used for the given baserunner situation.

However, in 2015, two teams bucked this trend. Both the Marlins and Cubs shifted on a higher percentage of balls in play with runners on base compared to when the bases were empty.

The only situation when the Marlins didn’t match or out-shift their bases-empty percentage (7.1 percent) was when they faced a runner on second (3.0 percent). We should note the Marlins only shifted 300 times in total last season, fourth-lowest in the majors. For the Cubbies, they didn’t match or out-shift their bases-empty percentage (10.5 percent) in two different base-occupancy states: with a runner on first (10.3 percent) and with runners on first and third (2.9 percent). And the Cubs only shifted 84 times more than the Marlins, tied for ninth-lowest in baseball.

On the other end of the spectrum, three teams shifted more than 75 percent less often when a runner reached base: the Twins, Mariners, and Tigers.

The Mariners finished last in shifting among American League teams in 2015 with 352 total shifts, while the Braves put up the lowest total among teams in the National League at 211.

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