PITTSBURGH -- One of the prospects acquired in the Brewers' biggest Trade Deadline deal a year ago underwent season-ending Tommy John surgery on Thursday.
Right-hander Adrian Houser, who pitched in two Major League games for Milwaukee last September, had the surgery in Milwaukee and is expected to be sidelined at least 12 months. Brewers head physician William Raasch performed the surgery.
Houser, 23, ranks 17th on MLBPipeline.com's current list of the top Brewers prospects. The Brewers acquired him from the Astros last July 30 along with three other top prospects -- pitcher Josh Hader and outfielders Brett Phillips and Domingo Santana -- for Carlos Gómez and Mike Fiers.
The Brewers did not make any announcement of the surgery, though Houser is on their 40-man roster. It was reported by the Milwaukee Journal Sentinel and subsequently confirmed by farm director Tom Flanagan.
Houser posted a statement on Twitter saying the surgery repaired a "significant" partial tear to his ulnar collateral ligament.
"This is just a bump in the road that I will work hard to overcome and come back stronger from," he wrote. "It's a long rehab process and I'm ready to get to work so I can get back to competing and helping the Brew Crew wherever I can in the future."  

Houser becomes the third member of Milwaukee's Top 30 Prospects list rehabbing from Tommy John surgery. Left-hander Nathan Kirby (No. 16 on the list) had it in September, just a few weeks after right-hander Taylor Williams (No. 22). The Brewers are hopeful that both will be participants in the fall instructional league.
"You realize injuries are part of it and you feel bad when it happens," Flanagan told the Journal Sentinel. "But at the same time, we know it's a surgery that has a very high success rate, and we're confident in our people to rehab Adrian and in Adrian to give the effort he's going to need."
Houser was 3-7 with a 5.25 ERA in 13 starts for Double-A Biloxi this season, but he was pitching well before the injury occurred. He had a 2.35 ERA in four starts in June.