Pierce Johnson, One Pitch Man

Pierce Johnson wasn’t the highest-profile addition the Padres made before the 2020 season. Johnson, a right-handed pitcher who began his career in the Cubs minor league system as a starter, transitioned to relieving and then transitioned to Hanshin in the NPB, where he delivered a standout 2019 season. Along with fellow offseason acquisitions Drew Pomeranz and Emilio Pagán, he was part of a reworked bullpen for a newly-aggressive contender.

Johnson’s 2020 went fairly well, aside from the whole global-pandemic-changing-the-entire-world part. He started throwing harder during his sojourn to Japan, and held that new velocity upon his return. His blend of roughly 50/50 fastballs and curves played quite well; he put up a 33.8% strikeout rate en route to 20 innings of 2.70 ERA, 3.14 FIP relief.

In truth, Johnson’s fastball was just a palate cleanser for his devastating curve. He used it early in counts and when he got behind, but threw nearly 75% curveballs in key spots — 1-0, 0-1, and 1-1 counts, as well as when he reached two strikes. It’s easy to see why when you look at the curveball’s merits. Among pitchers who threw at least 150 curves last year, it was one of the best in the game:

Best Curveballs, 2020
Player Pitches SwStr% Whiff/Swing
Shane Bieber 325 25.8% 51.5%
Drew Smyly 176 23.3% 50.0%
Aaron Nola 306 22.5% 41.8%
Pierce Johnson 168 22.0% 48.1%
Germán Márquez 311 21.9% 43.3%
Aaron Civale 254 20.5% 39.4%
Tyler Glasnow 335 20.0% 52.8%
Tyler Duffey 188 19.7% 41.6%
Jesús Luzardo 214 19.6% 45.7%
Framber Valdez 351 19.1% 41.9%

That’s excellent company, to state the obvious. It’s not as though the pitch is a wipeout breaker that only excels when he bounces it, either. In obvious strike-throwing counts (2-0, 2-1, 3-0, and 3-1) since returning from Japan, Johnson has hit the strike zone with his curveball 58.6% of the time. That’s higher than his fastball zone rate in the same counts (42.1%) and higher than the overall league zone rate for all pitches in those counts (56.9%).

In other words, the curve is both his best pitch to miss bats and his best pitch when he needs to throw something in the zone. Visually, this one looks gorgeous:

But it’s nice to have the ability to throw the pitch in the strike zone as well. This is the second of two straight curveballs Johnson threw Mike Trout, both for strikes, and Trout couldn’t pull the trigger on either one:

Finally, of course, there’s the brass ring — a curveball for a strike that still draws a swing and miss. Justin Turner takes a big hack here, but comes up empty:

To recap, Johnson’s curveball is his best pitch, and it’s not particularly close. Also to recap, he was throwing it equally as frequently as his fastball, a middle-of-the-road offering. If you’ve followed baseball in recent years, you know what’s coming: he started throwing his best pitch more often.

“More often” is an understatement. Johnson is going to the hook 73.4% of the time so far this season. That’s the highest mark for any pitcher since the start of pitch-level data, and it’s the highest by a lot; Joe Kelly threw 63.2% curves in 10 innings last year, which is good for second place. There are only 11 seasons of 50% or higher curveball usage, and Johnson accounts for two of them.

How do you throw 75% curveballs? You throw them early and often, in every count imaginable. Remember, Johnson was already an outlier in 2020; look how much he’s kicked it into overdrive in 2021:

Curveball Usage by Count
Count 2020 2021
0-0 57.5% 79.5%
0-1 51.1% 77.3%
0-2 74.1% 70.6%
1-0 46.4% 83.3%
1-1 63.0% 43.8%
1-2 72.7% 61.9%
2-0 15.4% 87.5%
2-1 53.8% 100.0%
2-2 63.6% 83.3%
3-0 0.0% 0.0%
3-1 11.1% 50.0%
3-2 57.1% 87.5%
Yellow = Higher usage between the two years

Look closely, and there’s something interesting going on. He’s throwing more curveballs in every count except three: 0-1, 0-2, and 1-2. None of those counts are screaming out for fastballs, and the sample sizes aren’t huge, but they’re actually interesting places to lean on the fastball at least a little bit; if the pitch isn’t your best pitch to spot for a strike, it can at least be an ambush offering in counts when batters are no doubt thinking “don’t swing at a curve, don’t swing at a curve.”

Other than those pitcher’s counts, though, Johnson is using his curve with wild abandon. It’s working; per our run values, his curve is nearly twice as valuable per pitch this year as compared to last year despite the increased frequency. It’s also more valuable, period: it’s been one of the best pitchers thrown by any reliever, full stop, so far this year.

Johnson might be alone when it comes to curveballs, but he’s part of a vanguard of pitchers throwing breaking balls more than two thirds of the time:

Breaking-First Pitchers
Pitcher SL% CU% ERA FIP xFIP
Austin Adams 88.5% 0 3.86 1.73 2.46
Matt Wisler 88.4% 0 6.75 3.70 3.95
Pierce Johnson 0 73.4% 3.18 1.51 2.88
Diego Castillo 69.2% 0 3.14 3.38 3.01
Luis Cessa 67.5% 0 2.40 3.76 4.28

Cessa hasn’t been good, but he’s walking 16.7% of opposing batters, so he might not quite have the command to use a breaking ball as his primary pitch. The rest of these pitchers are effective relievers, though, and they have two things in common: decent fastballs that don’t exactly demand to be used, and a nasty breaking ball they can locate for a strike.

Why are there multiple relievers who throw sliders nearly all the time, and only one who throws a curve? This is only a theory, but in the aggregate, sliders are easier to command than curveballs. Leaguewide, pitchers throw 51.5% of their sliders in the strike zone when they’re behind in the count. They locate only 48.6% of their curveballs in the zone. It’s not a huge difference, but anecdotally, pitchers seem more comfortable throwing sliders for strikes as well. Curveballs in the strike zone feel somehow defenseless — they’re slow, and if a hitter stays back on them, it can look like the ball is on a platter.

Perhaps unsurprisingly given that, Johnson’s curveball behaves a lot like a slider. Per Baseball Savant, it drops roughly four inches less than the average similar-velocity curve on its path to the plate. It also breaks four more inches horizontally than the average curve; it’s more two-plane than a pure rainbow curve.

In fact, the pitch behaves like a sort of hybrid. At 84 mph, it’s one of the fastest curveballs in the game, though it would be on the slow side for a slider. It’s light on transverse spin for a curve: most curves have transverse spin percentages in the upper 60s or higher, but Johnson’s checks in at 53.3%. That’s more than your average slider, but not egregiously so.

It’s still very much a curveball. That’s what Johnson calls it, and it’s what every pitch identification system thinks as well. In terms of how it moves, though, it’s something in between, which does a lot to explain why he can use it in such an idiosyncratic way.

Should other pitchers copy Johnson? I feel fine saying I have no clue. For one, he’s only 11.1 innings into his new plan to throw all curves all the time. We haven’t had enough time to see how hitters will adjust; only seven batters have even seen him more than once this year. Heck, we don’t know if Johnson will keep doing it; he’s only thrown 182 pitches, period, in 2021. In addition, there aren’t many curves like his; if you’re throwing a mid-70s lollipop, spotting it for a strike might not be so simple.

I’d like to see him succeed with this approach, though. It’s fun! Pitchers can feel same-y these days; we get it, every bullpen arm throws 96 with a wipeout slider. Seeing someone pitch so differently than the masses — weirdo pseudo-sliders for breakfast, lunch, and dinner — is a treat. Seriously, don’t act like this curveball down the middle on a 3-2 count isn’t fun:

Well, unless you’re Mike Tauchmann, who might still be staring into space wistfully:

More wistful stares! More curveballs in the strike zone! More curveballs in hitter’s counts! More curveballs forever! Pierce Johnson is the weirdest, and the best.

Ben is a writer at FanGraphs. He can be found on Twitter @_Ben_Clemens.

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One nit to pick. Stammen joined the Pads in 2017, you might be thinking of Pomeranz who rejoined San Diego in 2020 as a free agent.