You’ve Never Heard of Jonathan Hernández, but Maybe You Should Have

You shouldn’t trust spring training statistics. Opposition quality is, to put it kindly, uneven. Non-roster invitees and overmatched minor leaguers get their turns in the spotlight. A home run off Johnny Washedup or Mike Minorleague isn’t the same as one off a fifth starter, let alone Gerrit Cole.

So of course, today I want to talk about an off-the-radar reliever putting up good numbers in spring training. “But Ben,” you might say. “Did you read the paragraph that you yourself just wrote?” Good point, conveniently voiced reader. But here’s a trick to writing about spring training performances that might stick. I want to talk about Jonathan Hernández. And while he’s looked sharp this year, I want to talk about him not because he’s been good for the last month but because I think he was already good.

An origin story is in order. Hernández signed with the Rangers as an international free agent in 2013, when the Rangers were the unquestioned best team at finding international talent. He slowly but surely climbed the minor league ranks as a starter. His sinker/slider combination was good enough to tread water, but never dominant.

Early in his career, he’d shown excellent command. As he ascended the minors, he added exciting velocity to the sinker. But the command waned as the velocity increased, a classic tradeoff. In 2018, he walked 13% of the batters he faced in Double-A. We put him 19th on the Rangers prospect list heading into 2019, reflecting excitement about his velocity and concerns about a relief role.

In the middle of 2019, the Rangers cast a vote in the same direction. With Hernández still struggling as a starter, the team moved him to a multi-inning relief role. It didn’t fix everything, at least not completely — he recorded a 21.8% strikeout rate and 10.9% walk rate in the new role — but his stuff looked good enough in relief that the team called him up to the majors even before September roster expansions.

I’ll forgive you if you didn’t notice Hernández’s major league numbers last year. He looked like a generic reliever with control issues. He struck out 24.4% of opposing batters and walked 16.7% on his way to a mid-fours ERA and high-fours xFIP. If that’s all there were to him, I wouldn’t be writing this article. But his sinker (which Pitch Info classifies as a four-seamer) is enough to make me sit up and take notice.

The term “sinker” is something of a misnomer. They rise (excluding gravity) less than four-seam fastballs, which gives them their name, but the majority of most sinkers’ movement is horizontal. The pitch has arm-side run; it bores in on same-handed hitters and darts away from opposite-handed ones. And if you’re looking for horizontal movement, Hernández has what you need: his fastball averaged 10.06 inches of horizontal break in 2019.

Let’s take a quick look at pitchers who had similar movement profiles — movement within an inch in the horizontal plane and velocity within 1.5 mph either way:

Sinker Comparables
Player HMov (in) VMov (in) Velo (mph)
Jonathan Hernández -10.06 3.71 96.7
Blake Treinen -10.52 2.72 96.8
Luis Castillo -10.20 2.28 96.6
Jeurys Familia -9.79 3.12 96.1
Sandy Alcantara -9.57 4.07 95.7
Dustin May -9.41 4.72 96.2
José Ureña -9.40 4.79 96.4
Héctor Rondón -9.33 5.14 96.8
Robert Gsellman -9.31 6.04 95.6
Jake Diekman -9.29 4.60 96.0

That’s an intriguing list; not everyone on it is good, but everyone is at least interesting. Ureña is the only pitcher who might qualify as “bad,” but no one would say he doesn’t have the stuff to succeed.

Those are some nice abstract words, but I know what you’re thinking: let me see it in action. Alright then:

Trey Mancini gives up on that pitch early, because it looks like it can’t possibly catch the plate. If you’ll forgive the camera angle, you can see Tommy Pham mimic Mancini:

When Hernández starts the pitch over the plate, he gets the opposite look; watch Marcus Semien take a healthy hack at a pitch off the plate:

Those two locations are the key ingredients to a successful sinker. Drifting from the left-handed batter’s box over the plate is effective against righties, but it’s positively bone-chilling against lefties. Watch Hernández simultaneously brush Mallex Smith back and get a called strike:

Of course, man cannot live on one pitch alone. Hernández throws a slider that complements his sinker perfectly; it’s all glove-side run, with no vertical movement to speak of, and the two pitches break 13.5 inches opposite horizontally. Home plate is 17 inches wide. So when Semien struck out on a slider away…

He was swinging at a pitch that “should” have been within five or six inches of the previous pitch he’d swung through, which ended up off the plate inside.

The slider isn’t perfect. Hernández overthrows it from time to time, turning it into a back-up, cement mixer of a pitch. Still, it’s phenomenally effective as-is. Batters whiffed on nearly 50% of their swings against it in 2019, and even when they did make contact, it was largely harmless. Eight of the 10 balls in play he allowed off of the slider were grounders.

If the pitches I’ve shown in this article were perfectly representative of Hernández’s whole game, he wouldn’t be struggling to stick in the majors. His sinkers aren’t all corners and whiffs; he allowed three homers on the pitch in the big leagues last year, and two of those were left middle-middle.

That can happen to anyone, but his control is potentially more worrisome. A full 18% of his pitches were in what Baseball Savant calls the “waste” zone, so far off the plate that they rarely drew a swing. His 16.7% walk rate wasn’t particularly surprising in light of his struggles with command.

But if he can get the command straightened out, two plus pitches would immediately make him a bullpen force. He has a theoretically usable changeup he can mix in against lefties, and has shown an acceptable curve at times, but those hardly matter. The sinker and slider alone, properly harnessed, could turn him from a 5 ERA afterthought into a relief stud.

This winter, Hernández showed further signs of improvement. He pitched phenomenally well for Aguilas Cibaenas in the Dominican Winter League, striking out 35.6% of opposing batters while walking only 4.4% (admittedly in only 9.2 innings of work). This spring, he’s walked three batters out of 30 faced, which doesn’t sound great, but has also struck out 10, an acceptable ratio.

And oh yeah — he might not have unlocked his full potential as a reliever last year. Hernández hit 100 mph in an appearance, and he’s been clocking in more like 97-98 than 95-97. Move the pitch up to that velocity, and he starts to look a lot like Diego Castillo, only with more arm-side run.

As an added bonus, the Rangers bullpen is hardly a fortress that no outsider can infiltrate. José Leclerc is a perfectly serviceable closer, and Joely Rodríguez is a cipher with a promising splitter, but we’re not talking peak Royals or the 2019 Yankees here. We project Hernández for 30 innings pitched this year, and that could slide up to a full-time bullpen role quickly if he keeps the walks down and the velocity up.

It’s quite possible that Hernández will be merely another bullpen arm. After all, he had a 5.61 FIP in the majors last year, and he wasn’t exactly blowing the opposition away at Double-A before his call-up. But I’m an optimist. I don’t look at him and see past results. I look at him and see future potential, and all of baseball might be doing likewise by the end of this season.





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

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Johan Santa
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Wish you had a link to Mike Minorleague’s player page,.