SURPRISE, Ariz. -- As if Kelvin Herrera's 100-mph fastball wasn't enough, the Royals right-hander is polishing up a curveball for his arsenal.
"I'm trying to throw it more often now. That's what I'm going to work on my next outing," Herrera said.
That will be Saturday against the World Series champion Giants. So far he's pitched two scoreless innings, giving up three hits.
"I need to add a pitch this season," Herrera said. "It's a sweep curveball."
Manager Ned Yost said an effective curveball will make Herrera even more dominating than he was last year, when he posted a 2.35 ERA, four wins and three saves as a rookie.
"It's definitely the one thing that he needs to make a bit of an improvement on and be more consistent with," Yost said. "He basically throws strikes with his fastball, has a very good changeup and was a tad bit inconsistent with his breaking ball. If he can develop more consistency with his breaking ball, that gives him three above-average pitches that he can get guys out with."
This spring, Herrera has a secure hold on a bullpen spot. A year ago, he was a kid hoping to land a job.
"Last year, I was worried about where I was going to be," Herrera said.