The White Sox announced Wednesday that Michael Kopech, the organization's second-ranked prospect, underwent Tommy John surgery on Tuesday.
The procedure was performed by Dr. Neal ElAttrache in Los Angeles, and the 22-year-old right-hander is expected to miss the entire 2019 season but be ready for Spring Training in 2020.
"Obviously, it went well and I think he understands intellectually what it's going to require of him," White Sox skipper Rick Renteria told MLB.com on Wednesday. "And I'm sure that as driven as he is, he'll understand the heart it's going to take to continue to work through this.
"It's a patient process to make sure he comes through this as well as possible [and] to give himself a chance to be that guy we all believe he's gonna be once he's recovered."
Video: Kopech strikes out ninth batter for Knights
Kopech was promoted to the Major Leagues on Aug. 21 and made four starts for Chicago, posting a 5.02 ERA and 15 strikeouts and a pair of walks over 14 1/3 innings. Prior to his debut in The Show, the 2014 first-round pick spent the entire season with Triple-A Charlotte, where he was 7-7 with a 3.70 ERA, 1.27 WHIP and 170 strikeouts over 126 1/3 innings in 24 starts.
"It's been a whirlwind of emotions for me in the past couple of weeks, obviously," Kopech told MLB.com after learning he had a torn ulnar collateral ligament in his pitching elbow. "From just about my absolute peak to the absolute rock bottom for me. I think to say it's unexpected would be an understatement."
MLB.com's No. 13 overall prospect was dealt to Chicago as part of the trade that sent left-handed ace Chris Sale to the Red Sox in December 2016. The 6-foot-3, 205-pound hurler routinely lit up radar guns with a fastball that averaged 95.7 mph and touched triple digits regularly during his brief stint in the Majors. He also sports a plus slider and average changeup.
Kopech is one of seven White Sox prospects ranked among MLB.com's top 100 and, along with former Charlotte teammate Eloy Jimenez, was expected to be a big part of Chicago's move from a rebuilding club to a contending one, beginning in 2019. Instead, he joins Brent Honeywell, Hunter Greene and A.J. Puk as top 100 prospects who suffered serious elbow injuries this year. Sixth-ranked White Sox prospect Dane Dunning has been out since late June with a moderate right elbow sprain that the team said would not require surgery.