Patton said the injury occurred Sunday night in the parking garage of his Baltimore apartment, as he rolled his ankle but was able to steady himself. His ankle swelled up overnight and he alerted the team's training staff, who sent him for X-rays -- which came back negative -- during Monday's off-day.
Patton was the Orioles' lone lefty in the 'pen, so Baltimore traded for J.C. Romero on Monday to give manager Buck Showalter another option. Romero took the roster spot of Miguel Socolovich, who was optioned after Sunday's game and designated for assignment on Tuesday. Right-hander Steve Johnson was recalled from Triple-A Norfolk to take Patton's spot on the active roster and will be available in long relief the next few days.
"[It's] very, very, very frustrating," said Patton, who has a 2.58 ERA in 52 1/3 innings this season. "I haven't felt as good as I've felt recently on the mound my whole career. So it's very frustrating. It's frustrating for this team and the situation we are in.
"We are facing lineups that are heavy left-handed-hitting lineups, and I would be used a lot the next few days. I feel irresponsible that I put our guys in this situation."
Patton seemed pretty confident it would be the minimum 15-day stay on the DL, saying he would be back as soon as possible, which would be Aug. 28. The plan is for him to head to the team's Spring Training facility following Wednesday's team picture day.
Romero, who could have opted out of his deal with Cleveland on Wednesday, spent nearly two months with the Orioles after he was released by the Cardinals in May. But he never made it to the big league club until now, despite pitching well with Norfolk. The 36-year-old posted a 2.74 ERA in 23 Minor League innings this year after posting a 10.13 ERA in 11 games (eight innings) for St. Louis.
"It's not unfamiliar territory for me," Romero said of being the only lefty in a bullpen. "I've been blessed enough to be part of good bullpens in the past. The whole Triple-A experience for me was a very humbling experience, and it kind of opened my eyes a lot. But at the same time, I feel that it was a way of getting my arm back in shape and work hard. When I went to Triple-A, I didn't take anything for granted. I was going at it like I was in the big leagues. I guess it paid off."
Johnson, who was slated to start for Triple-A Norfolk on Tuesday, is a candidate to start Friday or Saturday, with Showalter committing only to Miguel Gonzalez and Chris Tillman starting following Wei-Yin Chen. Tommy Hunter would be slated to go after that, but it's not definite.
Brittany Ghiroli is a reporter for MLB.com. Read her blog, Britt's Bird Watch, and follow her on Twitter @britt_ghiroli. This story was not subject to the approval of Major League Baseball or its clubs.