Banning the shift probably wouldn’t impact the Mariners so much

Earlier, John wrote about the latest batch of rule changes MLB plans to guinea pig in the minors. No offense to the scintillating topic of bigger bags, but the thing so far that seems to be occupying the most column inches is the potential banning of the shift. Just to be clear: the new rule, which will only affect Double-A, only bans some kinds of shifts, specifying that all infielders have to have both feet on the dirt. This wouldn’t stop teams from moving infielders over to one side necessarily, but would ban, for example, the extreme “Joey Gallo shift” the Astros used against the Rangers back in 2018.

If you want a recap on why people are shift-haters, go read John’s article, where he summarizes it nicely for you in a paragraph with some other links where you can learn more. What we are doing here is not arguing whether or not the shift should be banned, but simply examining how, if the shift were banned, that would impact the Mariners.

When you think of which teams heavily utilize the shift, you probably think of teams well-known for analytics, like the Dodgers, Astros, and Rays. You’d be partially right: no team in baseball loves shifting as much as the Dodgers, who have led the league in each of the past two years, shifting almost 56% of the time in 2020, and just over half the time in 2019. The Astros shifted about half the time in 2019, second-most in baseball, but in 2020 dialed their shift down to 44%—behind other teams that had enthusiastically embraced the shift like the Tigers, Pirates, and Brewers. As for the Rays, they too have moderately scaled back their shifting; after ranking 4th in the league in 2019 (37%), they now shift about as often as the Mariners, who shifted 33% of the time in 2020, a significant uptick from 19% in 2019. Both years, the Mariners have ranked more towards the middle of the pack in shift utilization.

What’s more interesting with the Mariners isn’t how often they shift but who they shift against. The Mariners are one of the bottom-five teams in shifting against righties, and have been in both 2019 and 2020, but lately have begun to employ an aggressive shift against lefties: after shifting against LHH just 45% of the time in 2019 (still significantly higher than their percentage of shifts overall), that number jumped to 71% in 2020, 4th-most in the league and higher than even the Astros.

Most teams that heavily employ the shift do so for both lefty and righty batters, even if they shift righties slightly less than lefties. Why might the Mariners shift so heavily against LHBs and hardly at all against righties? Let’s take a peek at the heatmaps for a few of their starters in 2020 when facing lefty batters:

The Mariners’ strongest defenders in Kyle Seager and J.P. Crawford are on the left side of the infield, so it makes sense to shift them over for lefty batters, who have a propensity to hit the ball on the right side of the infield. However, with righty batters hitting the ball the opposite way, it makes more sense to leave the premium defenders where they are, without any additional help needed from whoever is manning second base. That explains the big gap in the Mariners’ shifting tendencies between batter handedness—the second largest gap in the majors in 2020, right behind Cincinnati.

If the shift were banned entirely, the Mariners, in their current iteration, would likely be less adversely affected than most teams in MLB that utilize the shift heavily against both righty and lefty batters. With Gold Glovers making up 3/4ths of the infield, the Mariners are able to provide a well-balanced attack without resorting to extreme measures like the Gallo shift. However, if/when Kyle Seager departs that will drastically change the face of the infield, especially if the Mariners fill his spot with a subpar defender like Ty France. In that case, banning unorthodox defensive positioning of any sort would be less than ideal for the Mariners.

Speaking of Seager, there’s been a lot of talk about how banning the shift would help him. It’s true that Seager is one of the most-shifted players in MLB; he was the 45th most shifted against player in 2020, at 76.3% of the time. However, despite the shift, Seager still managed a wOBA of .350 last year when facing the shift. Including Seager, there were only 12 batters in 2020 shifted on more than 75% of the time who maintained a wOBA against it of .350 or higher (Kyle’s brother Corey doesn’t qualify, as he was only shifted against 72% of the time. Sorry, Corey!). Last year, over a full season, there were only eight batters to clear that mark; Seager missed it, with a wOBA against the shift of .338, but that was also the season where he was dealing with some wrist issues. In 2020 Seager actually had a higher wOBA against the shift than when not facing it, and in 2019 it was almost an even split. In fact, dating back to 2016, the only year that was a significant wOBA dropoff for Seager shift vs. non-shift was 2017, with a stark difference of about 75 points. 2017 was the year after his five-win season, and perhaps that was when the “the shift is killing Kyle Seager” narrative firmly took hold. But if the shift were banned tomorrow, we likely wouldn’t see much of a noticeable difference for Seager, nor for the rest of the Mariners. Probably the people most affected by a complete ban on the shift would be the Mariners’ analytics staff who have spent years honing the perfect shift formula and will now have to go figure out the next cutting edge analytics breakthrough. I for one hope it has to do with jaunty bowties lending extra head stability and we all get to see some fresh bowtie fits take over the league.