What the data says about defensive shifts in Major League Baseball

DENVER, CO - APRIL 16: The New York Mets infield plays a defensive shift against Carlos Gonzalez of the Colorado Rockies at Coors Field on April 16, 2013 in Denver, Colorado. All uniformed team members are wearing jersey number 42 in honor of Jackie Robinson Day. (Photo by Doug Pensinger/Getty Images)
DENVER, CO - APRIL 16: The New York Mets infield plays a defensive shift against Carlos Gonzalez of the Colorado Rockies at Coors Field on April 16, 2013 in Denver, Colorado. All uniformed team members are wearing jersey number 42 in honor of Jackie Robinson Day. (Photo by Doug Pensinger/Getty Images) /
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CHICAGO, ILLINOIS – OCTOBER 12: Jose Altuve #27 of the Houston Astros turns a double play as Luis Robert #88 of the Chicago White Sox slides into second base during the 3rd inning of Game 4 of the American League Division Series at Guaranteed Rate Field on October 12, 2021 in Chicago, Illinois. (Photo by Jonathan Daniel/Getty Images)
CHICAGO, ILLINOIS – OCTOBER 12: Jose Altuve #27 of the Houston Astros turns a double play as Luis Robert #88 of the Chicago White Sox slides into second base during the 3rd inning of Game 4 of the American League Division Series at Guaranteed Rate Field on October 12, 2021 in Chicago, Illinois. (Photo by Jonathan Daniel/Getty Images) /

There is one baseball event that happens at a significantly reduced rate when playing against the shift, double plays. Over the last two seasons, 3.9% of all balls in play with no shift have resulted in a double play and only 2.3% have had the same result against the shift. When looking at the last six seasons those numbers are slightly closer, 3.4% and 2.5% respectively. That difference may be small but ground balls are about 25% less likely to result in a double play against a shift than with no shift over the past six years and 40% less likely over the past two seasons.

Put another way, based on the BABIP and double play information, over the course of 100 plate appearances against a shift in 2020 and 2021, a team will give up one less hit than they would without the shift. They will also convert one less ground ball into a double play.

How does the shift impact individual Major League Baseball players?

There has been a fair amount of analysis out there about the effect of the shift on individual players. It wouldn’t be surprising to me that some players are impacted more than others but it’s also apparent that because of extremely small sample sizes, the true impact of the shift on individuals is very difficult to measure, at least with publicly available data.

For a player like Gallo, FanGraphs has 0 PA where a ball was put in play with no shift in 2021 and one PA in the last three seasons combined. There simply isn’t enough data on how he fairs with no shift. What we do know about Gallo from 2021 is that 59.7% of his PA resulted in a HR, BB, K, or HBP. Of his 498 AB, 251 were either a HR or K and his average was .151 in those AB. Even Ted Williams in 1941 would hit below .300 if he hit that poorly in over 50% of his AB.

Now when you look at the league data, there are tens of thousands of data points that paint a picture of a slight advantage in reducing hits over the past two seasons by shifting but also a disadvantage in the ability to turn double plays. Across MLB in 2021, 36.3% of PA resulted in a HR, BB, K, or HBP. Compare that to the 29.7% of 20 years ago and it makes you wonder what the real reason is for the decline in offense.

Next. Why banning shifts won't fix anything. dark

Baseball teams are smart and have an unbelievable amount of data at their disposal. There must be significant, data-driven, reasoning put into their increased efforts to utilize shifting defensively. In the future, if some of that data becomes more readily available to the public, I look forward to going through it and seeing what it says. Until then, we have the wOBA data from Baseball Savant that indicates an advantage to the hitter when shifts are in place (at least to righties and no disadvantage to lefties) and the FanGraphs data that essentially says it’s a wash.