The fifth overall pick in last month's Draft gave up two hits and struck out five Saturday night as the Arizona League Royals posted a 5-0, five-inning victory over the AZL Padres.
Zimmer (1-0) did not issue a walk and did not allow a runner past first base before play was halted. Wynton Bernard singled to left field with one out in the third but was quickly erased when Felipe Blanco bounced into a double play.
Mallex Smith reached on a bunt single leading off the fourth, but Zimmer picked him off and set down his final five batters.
The Royals drafted the 20-year-old right-hander after he went 5-3 with a 2.85 ERA as a junior at the University of San Francisco. He recorded 104 strikeouts against only 17 walks over 88 1/3 innings for the Dons, earning third team All-America honors from Perfect Game.
After signing with Kansas City on June 7, the California native missed time recovering from a groin injury sustained in college. He made his pro debut on July 13 against the AZL Giants and allowed a run on two hits in two innings.
In his next start against the AZL Rangers on July 16, Zimmer yielded one hit and struck out five in three scoreless innings. Over 10 innings in three starts, he's given up one run on five hits with 13 strikeouts for a 0.90 ERA.