John Curtiss, Now With Control

Daily Graphings, Marlins

John Curtiss, Now With Control

When Kevin Goldstein previewed each NL team’s trade deadline reach-out calls earlier this week, he listed a smorgasbord of available Marlins. Corey Dickerson, Jesús Aguilar, Miguel Rojas, Starling Marte; if you’re looking for a hitter, the Fish have you covered. Want to shore up your pitching and catching? Sandy León, Yimi García, and Ross Detwiler say hello.

If I were calling the Marlins, though, I’d be tempted to skip that extensive selection and order off-menu, as you might with Wondee Siam or, if you’re less of a cheap New York dining hipster, In-N-Out Burger’s well-known but unlisted selections. Forget those brand name offerings; I’d be interested in finding out what it costs to get John Curtiss.

Curtiss hasn’t been a Marlin for life. He’s not an under-appreciated gem they’ve nurtured through their farm system. In fact, he started in the Twins system and excelled in the minors before scuffling (15 IP, 7.20 ERA) in two brief call-ups. The Twins shipped him to the Angels to ease a roster crunch, the Angels granted him free agency, and a brief stop with the Phillies ended with 12 poor minor league innings and a release.

That’s not quite a fairy tale story, but then things got interesting: the Rays, who know a thing or two about finding undervalued relievers, entered the picture. He carved through the AL East in 2020, but got shelled in the postseason. With the Rays facing a 40-man roster crunch (water is wet, the sky is blue, and the Rays have too many viable major leaguers), they traded him to the Marlins in exchange for Evan Edwards, a fourth-round pick in 2019.

The general story — the Rays turn a pitcher they found on the ground into a valuable draft pick — favors Tampa Bay, but in this case, Curtiss looks like a diamond in the rough. He’s always had some juice — he throws a mid-90s four-seamer and an upper-80’s slider, and both pitches miss their fair share of bats. He put up 30% strikeout rates nearly every year in the minors, and that’s mostly continued in the bigs.

Sounds great, right? Knowing that, and also knowing that he’s on his fifth organization, you can probably guess that there’s a “but” coming. Curtiss has had issues locating — and by issues locating, I mean that before 2020, he’d walked 10% of the batters he faced as a professional, and 12% since his ’17 major league debut. That’s too many walks! I’m hardly surprised that teams kept finding excuses to move on.

I cut that sample off before the 2020 season because I like making statistics misleading. Here’s a list of the pitchers with the lowest walk rates in baseball over the last two seasons, minimum 50 innings pitched:

Lowest Walk Rates, 2020-21
Pitcher IP BB%
John Curtiss 51 2.9%
Liam Hendriks 50.2 3.2%
Kyle Hendricks 150 3.6%
Craig Stammen 59.2 3.6%
Tommy Milone 53 3.7%
Zach Plesac 114 4.1%
Cole Irvin 73 4.1%
Zack Greinke 149.2 4.2%
Clayton Kershaw 134.2 4.2%
Nathan Eovaldi 115 4.4%

What is this sorcery? A guy who bounced around at least partially because of his elevated walk rates is now the walk-stingiest pitcher in the game? I want to know what’s going on, and I want to know now.

One way to lower your strike rate, at least historically, was to lean more on your fastball. It’s easier to command fastballs, the thinking goes, and so you can use that to avoid walks. There’s one problem with this theory: Curtiss isn’t throwing more fastballs. He’s throwing markedly fewer fastballs, in fact, 52.4% as compared to nearly 70% in his three previous major league cups of coffee.

Curtiss has used a newfangled strategy, a wave that is increasingly dominating pitching. He throws his breaking pitch for a strike now, and it’s transformed his game. From 2017-19, he threw 96 sliders and put 36 of them in the strike zone, a 37.5% rate. There’s nothing wrong with that; plenty of very good pitchers use their slider that way. Jacob deGrom has been throwing his that way this year — a 29.4% zone rate, eighth-lowest in baseball, and he’s pretty good. Liam Hendriks has the lowest slider zone rate in the game. It’s a reasonable way to use the pitch.

It doesn’t suit Curtiss, though, because he doesn’t use his slider the same way. Two thirds of Hendriks’ sliders have come with two strikes. More than 40% of deGrom’s have. They both lead with their fastball and use their slider as their out pitch — and in past seasons where deGrom used his slider more heavily early in the count, he threw it in the zone far more frequently. With a near-even split between his two pitches, Curtiss can’t wait for two strikes to bring out the breaking ball; only 34.5% of his sliders are thrown in two-strike counts. For him, it’s a key part of the arsenal in most counts.

This isn’t something you can just snap your fingers and do. Pitchers don’t just say “oh, I’d like to throw this slider for strikes” and then start doing it. It requires hard work, retraining your muscles to throw the pitch differently but still consistently, with similar break despite a different release point. But Curtiss did that, going from being a chase-only slider thrower to someone who uses his as a Swiss Army knife.

Consider two at-bats against Yankee sluggers. In 2019, Aaron Judge got ahead 1-0, and Curtiss tried to get him to chase:

It didn’t work, and then it was 2-0 to a dangerous hitter. Curtiss managed to coax a grounder, but he was working from behind, and situations like that frequently turn into walks. Next, consider this 1-0 pitch to Luke Voit last year, another slider with a different result:

What happened in this at-bat? Awkwardly enough, Voit hit a massive home run off of a middle-middle fastball later in the at-bat. But the tools to get back into the count worked — sliders in the strike zone that let Curtiss throw a secondary pitch without needing to hope for a swing. He’s throwing his slider in the zone 57% of the time when he’s even or behind in the count, well above the league-wide average of 48%.

This year, he’s done something else new, adding three ticks of velocity to the pitch even as his fastball has increased by only a single mile per hour. That hasn’t changed the shape of the slider overly much — he’s lost a smidgen of horizontal movement but added a tiny amount of drop — but it’s giving hitters less time to react without looking too similar to his fastball.

Curtiss’s new slider checks almost all the boxes I found when I looked into sliders a few weeks ago. He throws it 7.2 mph slower than his fastball, an optimal range. He throws it at nearly 88 mph, and fast sliders with at least a bit of horizontal movement — that’s his! — do well. He throws it in the strike zone more often, and again, yep, that’s what we’re looking for.

Honestly, most of those characteristics were there last year too. Heck, maybe the changes were already percolating before 2020, though it never showed in his zone or walk rates. Whatever the cause, though, I don’t see much reason to think that Curtiss will suddenly lose his ability to throw strikes and turn back into a high-walk pitcher again, and as it is right now he’s a valuable reliever.

There’s still one more change Curtiss could make to turbo-charge his results. Throwing breaking pitches in the strike zone is a good plan overall, but it stops being quite as good with two strikes. Here’s a table from the aforementioned slider article:

Run Value/100 with Two Strikes, 2020-21
Attack Zone RV/100
Heart 0.94
Shadow -3.62
Chase -1.54
Waste 4.36

The heart of the plate is a fine place to throw sliders early in the count, because batters often watch the pitch go by. When they’re in swing mode, though, leaving a pitch over the middle is a bad idea. We already know that Curtiss can keep the pitch out of the strike zone — he did that all the time earlier in his career. Now, though, he’s leaving too many over the heart of the plate with two strikes, and hunting for chases too infrequently.

I’m not positive that recapturing his old zone-light ways is an easy fix. Baseball isn’t a video game, and you can’t just choose to either lob one in or snap one off at will. It could be that Curtiss’s new muscle memory is changing his ability to execute chase pitches, leading to more pitches in the zone even when he doesn’t mean to locate them there.

Even if that is the case, though, it’s fine. Curtiss has been solid the last two years — he has a 2.47 ERA, 3.15 FIP, and 3.44 xFIP. He’s suppressed opposing barrels slightly and induced a decent number of pop ups. His 13% swinging strike rate is solidly above average. Curtiss was always a good pitcher — if it weren’t for those pesky walks. Now, he’s magically banished them, and despite his nonexistent pedigree, he looks like an arm that could help any contender.

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

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