Joey Gallo Swung Less, Except When it Was Good to Swing More

Joey Gallo cracked the code in 2019. He recorded his highest major league wRC+ (by far), his highest WAR total (in only half a season!), his highest walk rate, and his highest isolated power. Before fracturing his wrist in July, he looked like a second-tier MVP candidate. It was a clear step forward for a player who was already an above-average major leaguer.

It wasn’t all cotton candy and lollipops. His strikeout rate ticked up, from a yikes-gross-cover-your-eyes 35.9% to a seek-shelter-this-is-not-a-drill 38.4%. Gallo struck out nearly as many times, in under 300 plate appearances, as Michael Brantley has in nearly 1200 PA over the last two years. But despite the eye-popping strikeout rate, the overall package made Gallo one of the most fearsome hitters in baseball.

What did Gallo change to turbo-boost his game? He started swinging less. That’s not all he did, but it’s a lot of it. And for someone like Gallo, that makes a ton of sense. He has what Eric and Kiley call a grooved swing — his swing rides a consistent path, which makes it hard to adjust to pitches away from his preferred target area, and given how much damage he does when he connects, pitchers are doing their utmost to avoid that target area.

To wit: in 2019, 39.9% of the pitches Gallo saw were in the strike zone, a rate that would have been 30th-lowest in baseball if he had enough plate appearances to qualify. In 2018, it was even more severe; his 38.1% zone rate was fifth-lowest in baseball. In 2017, his 36.1% zone rate was the lowest in the majors.

Combine those low zone rates with Gallo’s abysmal contact rates, particularly on out-of-zone pitches (he’s been one of the worst two players in the majors in out-of-zone contact rate every single year of his career), and the calculus is clear: swing less, profit more. To make matters worse, Gallo isn’t even a particularly good bad-ball hitter; for his career, he’s produced a .336 wOBA when putting a ball outside the strike zone into play, which is only marginally better than the league average of .291. For comparison’s sake, he’s at .586 when making contact with a ball in the zone, while baseball as a whole comes in at .391.

Gallo’s chase rate fell from 32.2% to 24.2% in 2019. That’s 8% of pitches outside the strike zone that put Gallo ahead in the count instead of either being a poorly struck ball in play or a swinging strike. That came at the cost of lowering his zone swing rate by 8.9 percentage points, from 74.4% to 65.5%.

Last year, I came up with a framework to evaluate these swing decisions. Roughly speaking, the cost of swinging at a pitch outside the zone is the difference between the value of a ball and the value of your expected outcome given a swing. The cost of taking a strike is kind of the same; the difference between how much a called strike costs you and your expected return on a swing.

One important caveat: I prefer to strip two-strike counts out of the equation. The costs and benefits are so dramatically different than everything else that the situation merits its own analysis.

An out-of-zone swing costs Gallo, on average, 166 points of wOBA. The league average is 143 points, so he’s not the most extreme outlier, but it’s worth thinking about how big that gulf is. 166 points of wOBA is the difference between Mike Trout and Orlando Arcia. The swing hurts, is what I’m saying.

On the other hand, it’s not great for Gallo to take a pitch in the zone. Taking rather than swinging away costs him 102 points of wOBA. The reasoning behind this is pretty clear; he does whiff a decent amount, but when he makes contact, hoo boy does he make contact. Letting the ball go past when so much of his game is driven by power on contact within the strike zone is a fraught process.

Despite what I just said about the cost of taking a strike, the math is pretty clear. Swinging at a ball costs 166 points of wOBA. Taking a strike costs only 102 points. For every extra 1% of pitches outside the zone where he leaves the bat on his shoulder, he can afford to take 2.7% (percentage points, in both cases here) more pitches in the zone after accounting for the fact that well less than half the pitches he sees are in the strike zone. Given that he cut his chase rate by 8% while only lowering zone swings by 8.9%, he’s coming out well ahead in the deal.

There are interesting levels to this decision. If pitchers attack the zone more often, the cost of a zone take goes up (because it happens more frequently). That happened in 2019 — Gallo’s zone rate was the highest of his career. At the same time, that gives him the opportunity to dial up the aggression a bit — he’s now getting more pitches to hit, and the whole point of Joey Gallo is smashing hittable pitches. And of course, this math only makes sense on the margins. If he tried to swing at only 10% of pitches outside the zone, say, I doubt the breakevens established here would hold. But for small changes, they absolutely should, and that’s what Gallo did in 2019.

So that’s it, right? Swing less and profit. The equation seems pretty clear. Well, mostly that’s it. But we’re missing a key part of the swing decision tree. In all my math, you see, we’ve left out the issue of two-strike counts. They’re a corner case, but they’re also a major part of baseball.

A two-strike count does crazy things to your breakeven. Taking a strike is the end of the world. Swinging at a ball sounds bad, but it’s not as bad as you think: a ball doesn’t actually help you out very much, because you still have two strikes afterwards. It’s still bad to swing at a ball, because you’re unlikely to hit it, but you can at least be bailed out by putting the ball in play or fouling it off, and even a bad expected result on contact is okay when you’re facing down the crucible of a two-strike count. And swinging at a ball in the strike zone is like winning the lottery; when you make contact with two strikes, you’re turning a terrible situation into a great one.

If we run through the same math, but only look at Gallo when there are two strikes, the decision tree changes significantly. Not swinging at a strike costs Gallo 256 points of wOBA on average, while swinging at a ball costs him 277 points. Remove 3-2 counts, where swinging at a ball is death, and it costs him 245 points of wOBA to take a pitch in the zone, but only 207 points to swing at one out of the zone.

Basically, it makes sense to be a bit swing-happier with two strikes. The cost of taking a strike goes way up, and the value of taking a ball goes down. The major leagues as a whole certainly got the memo; in 2019, batters increased their swing rate by an average of 13 percentage points when facing two-strike counts.

That isn’t Gallo’s game — or at least, it wasn’t. Before 2019, he didn’t increase his swing rate at all with two strikes. He swung at 47.8% of non-two-strike pitches and 47.2% of two-strike pitches. When he pulled back on his overall swing rate, however, he did something clever. With fewer than two strikes, he swung 38.6% of the time. With two strikes, however, he swung 45.5% of the time, barely less than he had in the past.

Not only did he keep the valuable swings while cutting the situations where they were less useful, but he put up good two-strike discipline numbers as well. He chased only 22.3% of the time on two strikes while offering at 77.4% of pitches in the zone. Before 2019, he hadn’t been as judicious in chasing, swinging at 28.6% of pitches outside of the zone. Being more judicious with bad swings didn’t hurt him in the zone, either; he swung at 78.5% of pitches there from 2015-2018, barely higher than what he managed in 2019.

In other words, Joey Gallo figured it out. In situations where he had been giving away equity by swinging, he started swinging less. In situations where a swing is relatively more valuable, he kept swinging away at the same rate he always has. And he even improved his plate discipline in the bargain.

So with all those good things going on, why did Gallo’s strikeout rate jump? It’s merely the cost of optimization. It’s correct for Gallo to swing less often, as we just covered. A lot of the time, that leads to favorable counts and pitchers forced to meet Gallo where he wants them, in the strike zone. That’s the good outcome, and it happens enough that Gallo’s strategy is an overall success.

But there are downsides to keeping the bat on your shoulder, even if it’s a good strategy on the whole. Fewer swings means more favorable counts, but it also means more unfavorable counts and less early-count contact. The reason the overall package works is because many more plate appearances end in walks or with a ball in the strike zone getting walloped into outer space, but the cost of those outcomes is more deep counts and strikeouts.

Truth be told, Gallo’s strikeout rate is probably something he can’t fix. You can’t swing like Joey Gallo does and not whiff a decent amount of the time. But his new approach works within the constraints of his game, and it pushed his game to new levels. Can he keep it up in 2020? Who knows! His BABIP will surely drop, but it wouldn’t be a shock to see his strikeouts come down as well, as pitchers are forced to come to him in the zone more. I don’t know the future — but I do know that the 2019 version of Joey Gallo was his cleverest version yet.