Mike Zunino Powers Up

If you want to figure out who the most fearsome power hitters in the majors are, you can consider any number of criteria. The longest home runs? The hardest-hit batted balls? Those both make some sense. The raw number of home runs? Sure, why not? Personally, I like to look at barrels per swing — how frequently a given batter converts a swing into loud contact.

That’s often what we’re asking when we think about sluggers. If you hit 30 bombs but do it by swinging frequently and putting the ball in the air with average raw, that’s not really what I’d consider a slugger. Similarly, if you almost never make contact, I don’t care too much what happens when you do. Turning swings into smashed baseballs? That’s pretty much what I want to see.

The statistic has the added bonus of mostly passing the sniff test. Vladimir Guerrero Jr. and Shohei Ohtani are in the top 10. So are Ronald Acuña Jr., Fernando Tatis Jr., Yordan Alvarez, and Max Muncy. Some of this year’s fun surprises — Byron Buxton and Joey Votto — are on there, too. Aaron Judge is 11th. Who tops the list? I’m glad you asked:

That’s right: Mike Zunino is, by this metric at least, the best pure power hitter in baseball. He’s having a whale of a season, too, hitting .209/.296/.553, good for a strange-looking 131 wRC+. Though he’s barely above the Mendoza line, he’s clubbing enough homers (and it’s really just homers — he only has 10 doubles) and taking enough walks (9.4%) to make up for his ghastly 35.6% strikeout rate.

You’ve likely seen Zunino’s power on display in 2021. When Jay Jaffe wrote about extreme-angled homers, Zunino’s name popped up more than once. He’s made a habit out of knocking the stuffing out of the ball at extremely steep angles. Look at this beauty, a blast off of Brad Hand that gave the cameraman plenty of time to check out Kyle Schwarber’s footwork:

I’ll have more GIFs for you later, I promise. But first, you’ll have to sit through a discussion of what contributes to a high barrel-per-swing rate. Sorry! Those are just the rules here. We can’t declare Zunino the best power hitter in baseball without walking through why he’s great according to this very particular measurement of power.

If you want a lot of barrels per swing, you’re going to need a lot of barrels. That means two things: hitting the ball hard and putting it in the air. Neither have ever been a problem for Zunino. Want powerful hits? A full 37% of his batted balls this year have left his bat at 100 mph or more. That’s 21st in the majors, and it’s not some new skill. From 2019 to ’20, Zunino was putrid at the plate. He put up a .161/.233/.323 line, a 51 wRC+. He was also in the top 20 percent of all hitters when it came to hitting balls with triple digit exit velocities (85th out of 451 hitters with at least 100 batted balls). Hitting the ball hard certainly isn’t sufficient for success, but even when Zunino was going badly, no one questioned his power.

Next, you need to get the ball in the air. Yet again, that’s a Zunino specialty. This year, he’s hitting two fly balls for every grounder, the lowest GB/FB ratio for any batter with 300 or more plate appearances. It’s nothing new; he’s in the top 10% of the league when it comes to fly balls since reaching the majors. One look at his swing should give you a decent idea why:

That swing is perfect for getting low balls into the air. It’s also perfect for getting pitches over the heart of the plate into the air, and — when he connects — for getting pitches high in the strike zone into the air. If you’re looking for a batter who can get the most out of their batted balls by getting them airborne, look no further than Zunino.

That’s the barrels part covered — between his natural power and his exact swing, Zunino does a lot to get dangerous contact into the air. Next, we need the “per swing” part, and there Zunino has made great strides. It’s hard to get on this list if you’re a free swinger, because every empty swing hurts. In past years, that was a problem, as he swung more than half the time, roughly three percentage points more than the league as a whole. This year, he’s swinging slightly less than the average hitter.

That might not sound like a lot, but Zunino has seen 1,400 pitches this year. Three percent of that comes out to 42 extra swings, and if we added those swings to his yearly line, he’d be fourth in baseball instead of first in our cherry-picked metric. Now can we say that none of those swings would have been barreled? It seems unlikely. But generally speaking, getting rid of your worst swings will help out — he’s as aggressive as ever over the heart of the plate, where 31 of his 47 barrels have originated. That’s not a huge change, of course, but it’s like everything else in his profile: a marginal improvement that stacks with other marginal improvements.

It’s strange to think of someone who just came off of two years of offensive futility as being a few small adjustments away from stardom. Zunino was awful offensively in his previous two seasons in Tampa Bay. Are we supposed to believe he’s suddenly fixed? In a word: no. In five words: no, but maybe a little?

When players break out like Zunino has, they can do it one of two ways. One is optimizing their current skill set — swinging at more of the balls that they do the most damage on, for example, or getting aggressive on first pitches if they have problems late in counts. Maybe they swing more at fastballs, or take an approach that focuses more on high or low pitches. Zunino? He’s the second type of improvement — he just started hitting everything better:

If he continues to mash the ball at his current pace, the strikeouts just won’t matter. How likely is that? We don’t have an obvious cohort for Zunino, but I put together a rough test to find out. I looked at batters who improved their barrel rates meaningfully in the 2019 season (as compared to their 2015-18 production). Zunino’s barrel-per-swing mark ticked up by 3.9 percentage points between 2015-20 and this year. I picked those cutoffs to give us the largest possible Statcast-era sample. Here’s the group of players who made a similar leap in 2019: no one.

Fine, Zunino’s increase is off the charts. But the group of players that increased their barrel rates by at least two percentage points is more instructive: Howie Kendrick, Ketel Marte, Jason Castro, Jorge Soler, Christian Yelich, Dansby Swanson, and Anthony Rendon. They increased their barrels-per-swing rate by an average of 2.4 percentage points, from 2.4 percent up to 4.8 percent.

Kendrick didn’t play enough after that to meet a reasonable minimum, so I excluded him from the dataset. That leaves six players. I then looked at how they’ve performed in 2020 and ’21, particularly what percentage of their barrel rate gains carried over:

It’s a small cohort, but the group held on to 40% of their gains. If you expand it to everyone who improved by at least one percentage point, that makes for a 35-player group. That larger group kept 43% of their gains. In other words, it’s reasonable to expect that Zunino’s sudden improvement doesn’t mean he’s now the best pure power hitter in baseball — but it’s also reasonable to think he’ll hit for more power going forward than he had before this year.

Does that mean he’ll be a better hitter? That’s less clear, but that 35-player group improved by roughly 20 points of wRC+ between 2015-2018 and ’19. Their subsequent production was about eight points higher than the 2015-18 baseline. In other words, they held roughly 40% of their improvement. If Zunino follows that pattern — and it’s very much an estimate, not some statement of future fact — he’d be a 102 wRC+ hitter going forward. That sounds very close to what I would have estimated for him before generating a peer group — and in fact, our projection systems all peg him in roughly that area.

I know — “the best power hitter in the majors will be an average hitter going forward” is a pretty boring conclusion. It gets a lot more interesting when the hitter in question is a catcher, though. You see, the Rays didn’t target Zunino because they thought he’d be so valuable with his bat. They surely hoped for it, and the Rays have done well at helping their hitters improve, but the reason he’s on the team is for his sterling receiving skills.

In 2021, our framing metrics think Zunino has been about eight runs above average behind the plate. Given that he’s a catcher, that puts his defensive contributions at 16 runs above average — that’s what our DEF metric measures. What would an average hitter who adds 16 runs of value on defense every 350 PA look like WAR-wise? They’d be nearly a five-win player in a 600 PA season, an All-Star contributor, though that’s a ton of playing time for a catcher. At 400 PA, likely closer to what the Rays hope to give him, that’s something between 3 and 3.5 WAR, a hugely valuable catcher.

Combine that with a league-average backup, and you’d have one of the best catching situations in the game next year. You could argue that my estimate of his defense is too charitable, but it’s also conveniently very close to his average defensive value since 2015. Use Baseball Savant’s estimate of his framing, and he’d rack up 2.8 WAR instead — still enough to put the Rays in the top third of the league in catching value.

As it turns out, it’s really hard to find good offensive catchers who can hold their own behind the plate. Having an ugly line — and even in a good year, Zunino’s batting line is certainly ugly — doesn’t disqualify you from being a boon to your team. Is this a humdrum way of describing a guy who’s crushing the ball more frequently than anyone else in the major leagues? Well, yeah. But that makes Zunino a valuable player regardless, and since you’ve read so far, let’s watch one more home run. Here’s a warm St. Petersburg welcome to Jordan Montgomery: