The right-hander has struck out 65 batters and walked 22 in 52 innings.

"The grades are phenomenal on his pitches," Picollo said. "They’re all well above average. Anywhere from 60 to 80 (on an 20-80 scale) on his grades every night. As we start breaking down start by start, his pitch selection needs to get better. He’s just not going to be able to out-stuff hitters. He’s going through the learning process a little sooner than we expected. From a delivery standpoint and a stuff standpoint, it’s everything and then some. Right now, we have to be a little more patient than we anticipated. But that’s OK. I think in the end it will speed up (his development)."

Zimmer's had a few rough outings, which has resulted in a 4.03 ERA, but he has struck out 40 batters (tied for second in the Carolina League) in 29 innings and owns a .198 opponents' batting average. Zimmer is considered the Royals' second-best prospect by MLB.com.

"I don't really care about my stats individually as much as the team stats," Zimmer said, per MLB.com. "If I go out there and get a no-decision but the team wins, I could care less. As long as the team's getting 'W's,' it's what we're all trying to go out there and do."