Just before 5 p.m. Thursday, Kelvin Herrera milled about the visitors’ clubhouse at Minute Maid Park, a pair of earbuds planted in his ears. In 15 minutes, the Royals were set to stretch on the grass outside the third-base dugout. Herrera found a comfortable spot on a couch in the clubhouse, ready to enjoy a night off.
The break was well earned. On Wednesday, Herrera threw a scoreless inning while striking out two in the Royals’ 4-2 victory. On Tuesday, he did the same, racking up another two strikeouts in a spotless frame. Heading into Friday night’s game at Oakland, Herrera had allowed zero runs with eight strikeouts in five innings across five appearances.
The performance is not new for Herrera, who established himself as one of the best power relievers in baseball over the past two seasons. The method, though, has changed. After offering a glimpse of a new pitch during a dominant 2015 postseason run, Herrera has unleashed a restyled arsenal in 2016. The main difference: a slider that Herrera is using more than ever.
“I’m way different,” Herrera said. “Because I have a pitch to start an at-bat. I have a lot of confidence in it, and it’s helping my fastball. (I’m) getting more swing and miss.”
For most of his career, Herrera confounded hitters with a binary repertoire. He dialed up a fastball that could reach 100 mph. He kept hitters off balance with an effective change-up. But he never developed a reliable breaking ball. At one point, Herrera flirted with a curveball. It never took off.
That all changed last season, when Herrera spent most of the second half refining a new pitch with Royals pitching coach Dave Eiland.
“I started working on it in the second half, but I wasn’t throwing it that often,” Herrera said. “But in the playoffs, I just decided to throw it more. It was ready to go. I’ve got confidence in it.”
The results have been devastating for opposing hitters, albeit in a small sample size. Dating back to last postseason, Herrera has allowed just one earned run in his last 18 2/3 innings, including 30 strikeouts and five walks.
“He was primarily fastball/change-up,” Royals manager Ned Yost said. “He tried to throw a curveball, but he never could gain any consistency with it. So Dave tried to shorten it up and make it more of a true slider.”
A brief glance at advanced pitching data illustrates the difference. According to numbers from FanGraphs.com, Herrera used his fastball 83.5 percent of the time in 2015 and more than 78 percent for his career. This season, Herrera has thrown a fastball just 56.6 percent of the time, turning to his slider 19.3 percent of the time. He is still throwing change-ups nearly 16 percent of the time, which correlates with his career averages. But the slider has transformed what he can do on a mound.
Herrera says hitters can no longer sit on his fastball. They have to account for something that breaks. And in just months, Herrera has become rather adept at controlling the pitch.
“I can throw it for a strike,” Herrera said, “and I can also throw it for a strikeout.”
Herrera was already a crucial member of the Royals’ bullpen. He made his first All-Star Game in 2015. He has posted an ERA below 3.00 in three of the last four seasons. He helped the Royals to a World Series championship in 2015. Now he has added another pitch. His manager believes it could make him even better.
“That third pitch makes a big difference,” Yost said.