On Friday, he showed he'll have little trouble living up to that reputation as a professional.
The Royals prospect recorded a career-high 10 strikeouts and gave up three hits over 6 2/3 innings as Class A Kane County blanked Clinton, 5-0.
It was Zimmer's fourth Midwest League start and his seventh time taking the mound since signing with the Royals and receiving a $3 million bonus. In addition to establishing a personal best in strikeouts, Friday's outing was the longest of his brief pro career.
"Yeah, I think that was [my best pro start]," Zimmer said. "I think my command of all my pitches was there, I was hitting spots and getting ahead of guys.
"I was attacking early with the fastball, keeping it down in the zone and getting ahead with that. Then my off-speed stuff -- my curve, changeup and slider -- were all also working. I felt good. It was a good night."
Zimmer (1-2) led the West Coast Conference this year with 104 strikeouts and 10.6 strikeouts per nine innings. As a junior at USF, he posted a 2.85 ERA and walked only 17 in 88 1/3 innings. The 20-year-old right-hander fanned 10 or more batters in five of his 13 outings and finished 20th in the nation in strikeouts per nine innings.
So it wasn't too shocking when he displayed that kind of form against the LumberKings.
"I wasn't necessarily surprised [with the strikeout total]," he said. "I actually didn't know, I wasn't keeping track. I tried to take it pitch by pitch, hitter by hitter. But I knew I was getting ahead with two strikes and then just going for the punchout or keeping it down to get a groundball. And it worked."
The La Jolla, Calif., lowered his ERA with the Cougars to 4.32. Over 16 2/3 innings, he's fanned 23 while walking only five. Combined with three starts in the Rookie-level Arizona League, he's got a 3.04 ERA, 36 strikeouts and five walks in 26 2/3 innings.
Zimmer noted that one of the things he's worked on since joining the Royals organization is pitching out of the stretch with a slide step instead of the more open stance he featured in college. He's also moved from the first base side of the rubber to the third base side.
Despite moving from California to Arizona to Illinois, Zimmer said he feels like he's settled in pretty well.
"I think it always takes a little bit when you go to a new place, to settle in and fall into that routine. You sort of get that going after you've been there a little bit, and it's been a good adjustment here," he added.
"It's a little different at first, but everybody in this organization has been great. It's a lot of fun and I'm glad to be here."
Alex Llanos supported Zimmer with a pair of doubles and two RBIs, while leadoff man Justin Trapp tripled twice and scored once.