Zimmer, 20, was given a $3 million signing bonus as the fifth pick in the draft. Zimmer dominated rookie ball for 10 innings before being promoted to Single-A Kane County, where he posted a 2.43 ERA in 29.2 innings before being shut down. In the nearly 40 innings that he pitched overall, Zimmer struck out more than a batter per inning, while walking under two per nine.
Royals GM Dayton Moore insists that the surgery is more precautionary than anything, as the team wants to ensure that Zimmer won't miss any key development time during the 2013 season.
"Those loose bodies jump around in there and limit his range of motion, so instead of us having to do this in June of next year and he misses a month and a half, let's get it done now so he's ready to go."
Zimmer attended college at the University of San Francisco, originally committing there as a third baseman. In his final season, Zimmer struck out 104 batters in 88.1 innings pitched, while going 5-3 with a 2.85 ERA.