Why Kumar Rocker’s New Change-Up Matters More Than His Spring ERA

Kumar Rocker remains in the mix for the Texas Rangers’ fifth starter spot. His performance on Tuesday was rock solid.

The young right-hander made his longest appearance of the spring, as he threw four innings and 47 pitches, 36 of which were strikes. The Rangers want him to pound the strike zone more and that was the best he’s done it this spring. He gave up three hits — including a home run — and two runs. He also struck out five and walked none.

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The contest dropped his spring training ERA to 5.19. But that means little to the Rangers or to Rocker. This spring is about him showing mastery of one pitch — his new change-up.

Kumar Rocker’s Focus in Spring Training

Texas Rangers starting pitcher Kumar Rocker throws a pitch. — Texas Rangers starting pitcher Kumar Rocker. | David Frerker-Imagn Images

Rocker’s performance on Tuesday caught manager Skip Schumaker’s attention. The right-hander piggy-backed on Jacob deGrom’s start and threw 47 pitches. Per Statcast, only three of those pitches were change-ups, part of five different pitches he threw. That change-up induced one swing.

After the game, he was effusive in his praise of Rocker’s overall performance.

“12 of 15 first pitch strikes,” Schumaker said to MLB.com and other outlets. “The best I've seen him in spring, probably the best I've seen him live, quite honestly. He had the intent behind every pitch, the mound presence.”

The change-up is not going to be Rocker’s primary pitch. Far from it. On Tuesday he threw his sinker and his slider a combined 66% of the time. Those two pitches combined induced 22 swings, four called strikes and nine whiffs. Mixed with a fastball that can hit 97 mph, he has stuff most starters envy.

But Texas wants him to master the change-up and throw it for strikes to add off-speed balance to his arsenal. The three change-ups he threw on Tuesday average 89.1 mph. The sinker averaged 96.4 mph and the slider averaged 85.8 mph. Those three pitches, in combination with their movement, can do plenty to fool hitters.

Control was a significant issue last year and it’s part of the reason he was demoted to Triple-A in July. He induced an average chase rate (28.8%), an average whiff rate (24.9%), an average walk rate (8.0%) and a well-below strikeout rate (19.5%). Those rates should be higher for a pitcher with his stuff.

That’s where the change-up matters. If he can throw that pitch effectively and locate it in the zone, it further puts hitters off balance. That’s been his focus this spring and Tuesday’s game was another step forward.