What Banning the Shift Does And Does Not Accomplish

While the discourse surrounding the details of a new CBA has largely focused on economic issues, Sunday offered a glimpse into its potential impact on the playing field. In their proposal that day, the MLBPA agreed to grant the commissioner the ability to implement a pitch clock, larger bases, and restrictions on the shift for the 2023 season with less offseason notice than previously allowed (45 days compared to a year), per Evan Drellich of The Athletic.

Though no element of the new CBA has been finalized, it does seem likely that the league will be free to experiment with rule changes, given little incentive on the players’ part to resist them when broader matters are at stake. Already, there’s been speculation about how they’ll impact the game, with much of it concerning the demise of the infield shift. On the fantasy side, articles have popped up analyzing which hitters would benefit. On the social media side, there have been memes — lots of them.

On the FanGraphs side — well, let’s give it a shot! It’s a few days overdue, but late is better than never. There’s no guarantee that the commissioner will outlaw infield shifts, but if he does, what happens? Will the game be nudged in the right direction, or will its supposed problems worsen instead? What do we want out of a plan to ban the shift, anyways?

A huge part of it isn’t related to any numbers, but rather aesthetics. Consider how baseball is both a symmetrical and stationary game. It’s true that team sports designate positions to players corresponding to offensive or defensive roles, but in most cases, they come with the freedom to mingle and roam about. In soccer, varying formations are regarded as tradition, not experimentation. In football, there are seemingly endless amounts of routes and passes for teams to implement. In hockey, they play hockey.

Baseball is different. For decades, fielders have remained loyal to their assigned districts, moving only to respond to an incoming ball; even then, they take caution so as not to disrupt an adjacent teammate. Fans, players, and coaches have long understood this. The shift, in this context, is an incongruity that evokes a feeling of discomfort. When a hitter sends a ball through a gap created by an infield shift, we tend to focus on the aberration (the shift) rather than the outcome (a base hit). Likewise, when a line drive is snared by a second baseman in right field, the same out appears unnatural. It’s no wonder numerous fans want the shift gone. It’s also no wonder that they attribute this disruption of baseball’s law and order to a myriad of issues.

One example is a dearth of offensive production that — and this is important — occurs within the ballpark. Tune into any random major league game, and it does seem like the shift is gobbling up potential singles, doubles, and even triples left and right. Home runs are up instead, but to the chagrin of some fans, they don’t require much action; a trot around the bases suffices.

That assumption is true to a certain extent. It’s not as if the shift is some all-consuming vacuum, but select types of batted balls have indeed become much less valuable. For example, I used Baseball Savant to query batted balls hit hard (95 mph or above), pulled (a spray angle of 10 degrees or more), and relatively on the ground (a launch angle of 10 degrees or less) from left-handed hitters, who are more frequently shifted against. Here’s how the wOBA of this subset has diminished over recent years:

That’s a sharp decline, taking a relatively good result into a poor one. A problem arises, though, when extrapolating such numbers to describe individual hitters and the league as a whole. When images of ridiculous alignments are so memorable, it’s easy to forget that not every hitter is a lefty, a pull-happy lefty, or a pull-happy lefty who runs an above-average rate of groundballs. Those hard-hit grounders and line drives from earlier? They account for just about 3% of all batted balls in a given season. There are other types of batted balls impacted by the shift, like the up-the-middle hit, but these represent the minority rather than the majority. For every José Ramírez or Max Muncy, there are a dozen others with dissimilar traits.

To that end, I’d like to present a graph. It’s a plot of the league-wide BABIP produced by position players since 2002, the first season FanGraphs for which has that data:

Ignore the zoomed-in y-axis, which exaggerates minute changes. What matters is that the league-average BABIP hasn’t changed as much as one might have thought. From 2002 to ’19, it mostly hovered around the .300 mark. There’s been a noticeable downturn in the past two years that suggests a need for a ban on infield shifts, but if we’re considering fan satisfaction and experience, the argument doesn’t hold up. In 2019, the league-average BABIP was .299; in ’21, it was .293. The difference between the two is a mere six hits per 1,000 balls in play. Does the average fan watch enough baseball to parse that absence? I don’t think so.

But we can afford a more granular look, using Statcast data from 2015 onwards to look at changes in BABIP on groundballs, line drives, and fly balls. Maybe this will provide a clearer trend to analyze:

Things are… mostly the same. For some reason, fly ball BABIP is up compared to a few years ago. Groundball BABIP is down, but similar to overall BABIP, the difference is about five, maybe six points. Line drive BABIP has merely fluctuated. While the shift covers certain areas, it opens up others, meaning that BABIP hasn’t really plummeted no matter how one slices the data. Pulled grounders are less valuable than ever, but at the same time, opposite-field grounders are more valuable than ever, and league-wide batted ball tendencies haven’t budged.

Banning the shift isn’t only about balls in play, however. The thinking goes that the recent emphasis on launch angle and exit velocity is partially a response to an increase in infield shifts. Hitting the ball over the fielders’ heads renders any defensive alignment useless, after all. And it’s this approach that’s driving the uptick in strikeouts. Why does Joey Gallo rack up so many whiffs? Maybe because he’s conscious of the shift and is aiming for the fences instead of looking to make contact.

Besides the fact that there’s no definitive proof an uppercut swing leads to more strikeouts, I’m also not sure banning the shift incentivizes a hitter like Gallo to change his behavior. The pull-side would open up, but to take advantage of it, he’d have to completely revamp his swing. What do I mean by this? This is something Jeff Sullivan pointed out years ago, and I’ve recreated his findings with data from the past three seasons. Here’s the relationship between a hitter’s pulled groundball rate and overall groundball rate:

The hitters with a tendency to pull their grounders often record the lowest groundball rates. In other words, the hitter who seem like beneficiaries of a shift-less environment don’t actually have much to gain. If anything, removing the shift also removes the downside in adopting a pull-heavy, air-oriented approach, and if we’re to believe that strikeouts go hand-in-hand with “launch angle” swings, a ban on the shift likely won’t have the desired effect.

So are shifts irrelevant to strikeout rates? Not at all! In fact, the shift’s ability to influence them might be its greatest strength — and weakness. Russell Carleton of Baseball Prospectus is the foremost expert on the shift, and one of his many discoveries is how it disproportionately affects left- and right-handed batters. To provide a brief summary: the shift produces an unintentional “walk penalty” due to pitchers’ tendencies to nibble around the edges with a shift behind them. Lefties swing more often with the shift on, though, and see an increase in strikeouts from chasing outside the zone. But righties swing less often with the shift on, leading to fewer strikeouts and more walks.

All in all, it’s safe to assume the shift is a responsible for a slight increase in strikeouts, since lefties and righties don’t cancel each other out completely. But the emphasis is on “slight.” While writing this article, Carleton published his own thoughts on the proposed shift ban, in which he estimated the league-wide reduction in strikeouts to be a “per PA rate of 0.4 percent.” That’s an extremely small decrease, one that no human would notice unless it were pointed out to them. It tracks with the data on batted balls from earlier. BABIP has gone down, but to an extent only visible on a spreadsheet.

So what a ban on the infield shift accomplishes is two things. One, it restores a sense of normalcy to the game. No longer is a ball yanked past the three hole an automatic out, and no longer is a bunt against a shift an automatic single or double. Two, it buoys the production of a specific group of hitters, which probably includes at least one lefty from your favorite team. What it won’t accomplish is becoming a cure-all for MLB’s strikeout or pace-of-play ailments. Even with those pesky shifts gone, the game should hum along as usual. Sounds like a lot of hoopla about a strategic choice.