Michael Kopech had recently joined the Chicago White Sox rotation after years of being heralded as a top prospect. Four starts into his big-league career, he'd shown some of why he's considered a potential future front-of-the-rotation starter.

Unfortunately, Kopech will miss the rest of the season and potentially all of 2019 after tearing his ulnar collateral ligament and likely undergoing Tommy John surgery, per the team:

Kopech had tallied a 5.02 ERA and 13 more strikeouts in 14 1/3 innings. Most of that damage occurred in his most recent outing, as he permitted seven runs, all earned, in 3 1/3 innings. Before that, he had allowed one run or fewer each time out.

It's an unfortunate development for Kopech for reasons other than the obvious. While command and control had been his biggest blemishes in the past, recently he'd taken to throwing more and better strikes after slowing down his delivery. In fact, Kopech had walked just two of the first 68 batters he'd faced -- this from someone who had walked 4.4 per nine during his minor-league career. Now, Kopech will have to attempt to retain those seeming gains while working his way back from a layoff and grueling rehab.

This also disrupts (and potentially derails) any plans the White Sox had of competing next season. Prospects Eloy Jimenez, Dylan Cease, Dave Dunning, Zack Collins, and Alec Hansen are all expected to join the roster before 2020 rolls around. As such, the White Sox may not consider their competitive window fully opened until Kopech comes back.