The slider has hurt Royals closer Kelvin Herrera, but here’s why he’ll keep throwing it

Royals closer Kelvin Herrera talks about throwing his slider

Kansas City Royals pitcher Kelvin Herrera talks about throwing his slider this year.
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Kansas City Royals pitcher Kelvin Herrera talks about throwing his slider this year.

The pitch was born during the second half of the 2015 season, in the months before a deep playoff run. Reliever Kelvin Herrera saw it as the next phase of his development.

From 2012 to 2015, the hard-throwing right-hander had grown into a premium reliever on the strength of two pitches: A 100 mph fastball and a filthy change-up. As October approached in 2015, he went to work on a third pitch: A slider.

The pitch became a devastating weapon in the postseason as Herrera allowed just one run in 13  2/3 innings, including three scoreless innings in a decisive World Series Game 5 in New York. It became a full-time part of his arsenal in 2016. After throwing fastballs or change-ups 94 percent of the time in 2015 — including fastballs 76.3 percent of the time — Herrera began using his slider nearly 16 percent of the time. His change-up usage remained nearly flat, yet his fastball usage declined to a career-low 60 percent.

At the end of the season, Herrera had posted a 2.75 ERA and made another All-Star team. He credited the slider with a strikeout rate (10.75 per nine innings) that increased to its highest mark since 2013.

“I can throw it for a strike,” Herrera said last year, “And I can also throw it for a strikeout.”

But then came the start of the 2017 season, and the pitch surfaced again — and not in a good way. Herrera allowed two solo homers in his first three appearances, including a game-tying, ninth-inning blast to Jake Marisnick in a blown save in Houston on April 9.

Both of the homers came on sliders. How rare was that? Last year, Herrera allowed just two homers on sliders during the entire season.

Yet in the aftermath of the second homer, a solo shot surrendered to Rajai Davis on Thursday night, Herrera said he still felt confident in the slider. He didn’t regret the pitch selection, he said. It was just a couple of bad pitches.

“It was just poor execution on those,” he said.

So let’s look at each slider in question. Here is a look at the first one to Marisnick:

It’s unlikely that Marisnick would have been able to turn on Herrera’s fastball and hit a baseball out of Minute Maid Park. Herrera was also hurt by the small dimensions in Houston.

The second homer came on a hanging slider to Davis. Herrera shook off the mistake and recorded a save in a 3-1 victory on Thursday. The problem, Herrera said, was again execution — not pitch selection.

“I’m just trying to throw it down and away, make them chase it,” Herrera said. “I don’t want to throw it for a strike.”

The results have not been all bad. According to Pitch f/x data, Herrera is throwing his slider nearly 20 percent of the time this year. That’s slightly more than last year, and the number includes a more effective pitch that Davis fouled off earlier in the at-bat and a slider that induced a ground-out from Oakland’s Ryon Healy in the same inning.

In his appearance Saturday night, Herrerra threw just one first-pitch slider for a ball before recording his second save. In another outing against the Angels on Sunday, he didn’t throw a slider while working a clean ninth and earning the win. In his estimation, the problems have been poor execution in a small sample. The numbers didn’t look great after four appearances — Herrera had just two strikeouts while allowing two runs. But in his view, he is not too far away from his All-Star form.

“It was a new pitch,” Herrera said of the slider. “Now I feel like they’re expecting it. But I’m going to keep throwing it.”