"It's somewhat expected with some guys coming out of the draft now," Melvin said. "You just hate for it to happen to your guy. You'd rather him have it earlier than later and get it out of the way."
Ranked as Milwaukee's No. 14 prospect by MLBPipeline.com, Kirby fell to the Brewers in the Competitive Balance Round A due in part to missing nine weeks of his junior season at the University of Virginia because of a muscle strain behind his left shoulder.
Kirby returned from injury to pitch 4 2/3 innings for Virginia in the College World Series, including two scoreless innings to earn the save in the championship-clinching game for the Cavaliers.
An undisclosed medical condition delayed Kirby's signing with the Brewers, which was initially to be for a signing bonus of $1.548 million. The left-hander eventually signed for $1.25 million on July 17.
Kirby made his professional debut with Class A Wisconsin on Aug. 2 and was 0-1 with a 5.68 ERA in 12 2/3 innings for the Timber Rattlers before landing on the disabled list.
If Kirby does have Tommy John surgery, he'll be the second Brewers pitching prospect to undergo the procedure this season, as right-hander Taylor Williams had the surgery on August 11.
Andrew Gruman is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.