Kelvin Herrera’s New Twist

There’s something that would bother me about Kelvin Herrera. To be clear, it had nothing to do with his personality. And it had nothing to do with the fact that he was successful. Herrera should be successful. Have you watched him? The last two years, he’s run a 2.06 ERA. He’s allowed a .570 OPS, and while maybe that doesn’t mean a lot to you without context, how about this as context — Kenley Jansen has allowed a .569 OPS. David Robertson, .581. The numbers have been there for Herrera. He’s been a reliever with a triple-digit fastball and some statistics to match. Nothing about that is weird.

What would bother me was that, just from watching Herrera for a few minutes, you’d think he’d be a high-strikeout pitcher. Just from being aware of his velocity, you’d think he’d be a high-strikeout pitcher. I know we might make too much of strikeouts around here. I know I shouldn’t have been too bothered when Herrera was still finding ways to succeed. But the last two years, he’s been a flamethrower with the same strikeout rate as Chad Qualls. Compared to the league, Herrera actually ran a strikeout rate that was slightly below average for a reliever. It’s a small thing, maybe a petty thing, but it’s a thing my brain struggled to understand. Whenever I looked at Herrera’s numbers, I’d expect them to be something different.

Something like, say, what Herrera’s done in these playoffs. Since really emerging as a shutdown reliever for the Royals, Herrera’s struck out a little more than a fifth of the hitters he’s faced. Against the Astros and Blue Jays, however, he’s struck out about half of the hitters he’s faced. Herrera in this postseason: 33 batters, 16 strikeouts, .438 OPS. The heat, as you know, has been there. But it’s been accompanied by something different, something new. Kelvin Herrera tinkered with a slider, and he learned to harness it just in time.

When Herrera was younger, his breaking ball was a curve. As he moved into and got used to the bullpen, the curve almost went away, with Herrera settling on his big fastball and a quality changeup. Every so often a curve would get mixed in, but it wasn’t really recognized as one of his pitches. Even this year, in the first half, Herrera spun a curve from time to time. But it wasn’t a reliable pitch. Herrera was in the market for a third pitch — not because it was necessary, but because he thought it could make him better. Herrera started trying to develop a slider. You don’t just get confidence in a new pitch right away, but the usage clearly shows that Herrera is feeling good in the right month.

  • 1st Half: 4% breaking balls
  • 2nd Half: 7%
  • Playoffs: 25%

It’s like he’s a different pitcher. Really, first and foremost, he’s the same pitcher — he’s the guy with a harder fastball than almost anyone else. But now Herrera’s mixing in a breaking ball with great frequency, and this month his changeup has just about been put away in storage. Part of that is because, this month, Herrera has mostly faced righties, but now he’s even better equipped to put them away. And you’ve already seen his strikeout count. Righties in particular now need to respect something other than 100 at the belt. The fastball is difficult enough when it’s almost all that you know about.

Here’s Herrera putting Jose Bautista away in an at-bat that earlier featured heat inside:

It’s not a clean full swing and miss, but it shows up the same as one. And, it was a complete blowout, but it’s not like Bautista is one to take a plate appearance off. Herrera got Bautista to commit to a pair of sliders in that at-bat. Now, here’s Herrera surprising Chris Colabello on the first pitch:

Colabello looked unprepared. The same goes here for Russell Martin:

Think about what it took to throw those pitches. Those last two were both first pitches from Game 6, when the Royals led by one with the World Series calling. Both Colabello and Martin are plenty powerful, but Herrera still believed in the slider enough to go for the element of relative surprise. In the season’s second half, when Herrera’s slider was new, it was almost always limited to two-strike counts. Mediocre breaking balls can be effective two-strike breaking balls. In the playoffs, only about a third of Herrera’s sliders have come with two strikes. His overall usage of the pitch shows his heightened confidence in it. And his more specific usage patterns show his heightened confidence in it. Herrera didn’t need a breaking ball, but now that he has one, the results are what you’d expect.

His fastball breaks a good deal arm-side. His changeup breaks a good deal arm-side. His slider breaks a good deal glove-side, with more than seven inches of run. Based on movement, it’s actually a fair comparison for Jose Fernandez’s breaking ball. And Herrera has figured out his delivery and control. As a consequence, the majority of Herrera’s postseason sliders have been strikes, and the majority of the swings at the slider have missed. I don’t even think the Royals planned on this, but a neat way to not miss Greg Holland is to have one of your other relievers take his numbers to the moon. Herrera was already effective, but now he’s pitching like another closer. The guy blessed with the fastball suddenly has two other things.

I don’t know if it’s fair to say Herrera’s going to shock the Mets. They’ve certainly picked up on what he’s doing, and Yoenis Cespedes is the only Met to have faced Herrera more than once. (He has faced him twice.) So there’s not a big rich history. The Mets will try to prepare their hitters for the Royals bullpen, using the most up-to-date information. But preparation can do only so much. When it comes right down to it, Kelvin Herrera has a slider now, and he’s not even the most terrifying guy in the group. The goal: score early. They’re probably going to have to if they don’t want this to suck.

Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.

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7 years ago

Am a Mets fan, keep hearing how amazing the Royals bullpen is, know this to be true.

My question is: how amazing are they, quantifiably? Like, if you z-score AL playoff/AL Pennant winning bullpens over the past 10 years by -FIP, how many standard deviations is this KC Penn. Are they one standard deviation better than the average World Series bullpen? That’s scary. 1.5, 2? Terrifying.

7 years ago
Reply to  Borigh

They’re really good.