Carlos Hernandez and the curious case of great stuff

Kansas City Royals right-handed pitcher Carlos Hernandez is instantly recognizable. He’s huge, for one thing; listed at 6’4” and 250lbs, Hernandez looks like an NFL tight end on the pitchers’ mound. But watch him throw the ball and you’ll probably spot a 100 MPH fastball sooner rather than later, a skill that only a minority of the best pitchers in the world have.

In other words, He’s got some stuff.

Matheny has indicated he believes Hernández has what it takes to be a starter at this level moving forward.

“His stuff looked so good coming out of the ‘pen,” Matheny said. “He wasn’t overthinking. That’s still what we want him to do now as a starter. Let’s see how he handles this. I’m anxious to see him work in the first [inning].”

Such good stuff that we don’t need to worry about results so much.

The 23-year-old pitching prospect had a 1.42 ERA in 6.1 innings (two appearances) out of the bullpen this season, with this marking his first big-league start. He has good stuff, boasting a mid-90s fastball with good sink that can touch 99 mph, but Hernandez had never pitched above Low-A prior to this season, so we shouldn’t worry about the results.

Stuff! Stuff! Stuff!

Hernández, too, has made significant strides in his delivery working with Royals coaches, allowing him to harness the 98-100 mph fastball.

“You’re talking two guys with big stuff that could come in as starters or be those potential leverage guys in the bullpen, as well,” Matheny said. “It’s impressive to watch them take that next step. Having the big stuff, but having inconsistencies with it, and a lot of it has been mechanical adjustments to simplify and make it repeatable. I think it’s a difference-maker.”

Even Hernandez’s scouting report from 2018 suggested that he has lots of stuff.

There is risk in Hernandez’ present rawness and proximity to the big leagues. This profile often winds up in the bullpen, though his physical frame and good stuff will give him every chance to develop in the rotation. Ticketed for Class A Lexington, Hernandez is an under-the-radar prospect with breakout potential.

But what, exactly, is stuff? Well, if you’re wondering what exactly it is, you’re probably going to continue wondering. Still, two quotes from a 2015 New York Times article about stuff help to define what on earth stuff is pretty well.

[John] Smoltz himself took several attempts before settling on a definition.

“Stuff is something that will make a hitter very uncomfortable,” he said. Then he amended it with less-succinct explanations.

The word is both meaningful and meaningless. There are no synonyms. Like pornography, stuff is defined mostly by example. And only pitchers have stuff. Hitters do not have stuff.

“Hitters got tools,” [Ryan] Dempster said. “We never say the pitchers got tools. We say the pitchers got stuff.”

If I were to take a humble stab at the definition of stuff, it would be that stuff is just another word that describes the nastiness of a pitcher’s pitches. Confused? Well, the comparison to hitter tools by Dempster is pretty apt. A position player’s tools describe his raw ability in a number of different facets. Likewise, a pitcher’s stuff describes his talent via his pitches. Not everyone can throw 100 MPH. Likewise, not everyone can spin a breaking ball at 3000 RPM, or perfectly locate a changeup down in the zone—just like not everyone is fast enough to reliably steal a base, and not everyone has the power to hit balls out of the yard with regularity.

Unfortunately for position players, baseball isn’t just an athletic contest. Rather, it’s a skills contest that utilizes athleticism as its paintbrush. That’s why uber-athletes like Bubba Starling and Billy Beane can fail. Raw athleticism can only get you so far. And, importantly, it’s why stuff isn’t everything: throwing hard and having a sharp breaking ball only matters if you are skilled enough to use them to their greatest effect.

Hernandez boasts one of the most explosive fastballs in Major League Baseball. This year, Baseball Savant ranks him in the 98th percentile of average fastball velocity, and his fastball spin rate puts him in the 76th percentile. The fastest pitch he’s thrown this year was 100.7 MPH, and he throws triple-digit speed 15% of the time he throws the pitch.

But while stuff can get you far, you simply need more than stuff to win. This is exhibit A:

Here, Hernandez throws a fastball on the corner of the plate to Rafael Devers. But Hernandez misses his mark; Perez sets up just outside the plate on the other side. It’s a 99.2 MPH fastball that Devers hammers with an exit velocity of 112.1 MPH. It easily clears center field at Kauffman Stadium.

Exhibit B is here:

Hernandez tosses a changeup at 89 MPH, but it has minimal movement and is just a nice, slow meatball over the middle of the plate. Jeimer Candelario crushes it at 104.5 MPH to straightaway center—almost exactly where Devers hit his home run a month earlier.

And finally, exhibit C:

This is from last year, but the result was just about the same as the other two—just from a curveball. Perez calls a curveball below the plate, but Hernandez misses middle-middle. Bryan Reynolds makes an easy swing and sends it at 104.7 MPH to center.

Now, you can pull any three home runs for a pitcher from a 40-inning sample and point out that they were bad pitches. But these are illustrations of Hernandez’s downfall: he has the stuff, but he doesn’t have the command or consistency to utilize it. In his career so far, Herndandez has a 5.65 ERA. He has a 5.00 FIP. He has a strikeout-to-walk ratio at 1.81. He’s just not getting it done. And with a 4.44 ERA and a 5.39 FIP in 26.1 Triple-A innings, there’s not a lot of statistical evidence that he can get good hitters out consistently.

Because that’s what it is ultimately about: we know that faster fastballs perform better than slower ones. But baseball isn’t about throwing fastballs. It’s not about having stuff. It’s about getting hitters out. Sometimes a player isn’t as good as the sum of his pitches, just like a position player sometimes isn’t as good as the sum of his athleticism.

Hernandez will continue to get chances because he can throw a fastball quicker than nearly every human alive, including those who get paid millions of dollars to do so. But I can’t but be reminded of one other guy with stuff: Jorge Lopez, who has continued to get chance after chance. He’s currently with the Baltimor Orioles, who, after four years of consistently bad results and no track record of success in the upper minors, is still dazzling people with his stuff.

He’ll be eligible for salary arbitration for the 2022 season, and being out of minor league options, there’s always the possibility that his high-octane stuff could transition to a relief role where many believe he could thrive if he’s pushed out of the rotation by a younger pitcher.

For now, though, López will get ample opportunity to deliver on the long-held promise that his vibrant pitch mix might eventually make him an above-average starter in the big leagues.

Unlike Lopez, who turns 29 before next year’s Spring Training, Hernandez is four years younger and has some true upside. There’s no real harm in having him in the big league bullpen in a lost season. However, it’s easy to get blinded by the raw talent. Sometimes that raw talent doesn’t translate into great pitching. Stuff won’t be enough to cut it for Hernandez to succeed.