"We need to get through tomorrow night's game and then clear a roster spot," Trembley said. "You bounce it back and forth a lot, you hope the decision you make is the right one. You know in this game, especially starting off the year, there's going to be movement back and forth."
The Orioles decided to come north from Spring Training in Fort Lauderdale, Fla., with a 12-man pitching staff and a four-man bench. Acquiring infielder Robert Andino from Florida in exchange for once-heralded pitching prospect Hayden Penn on April 1 cemented that alignment, one that could change before Eaton takes the hill Sunday against Tampa Bay.
Andino is the only Oriole not to have started a game this season, while Trembley's bullpen has been taxed in the early going because pitchers aren't stretched out and starters haven't worked deep into games.
Because Andino is out of options, he can't be optioned without passing through waivers, and several other teams were interested in dealing for him when he was with the Marlins. A relief pitcher would appear to be the likely candidate for the necessary roster move, but Trembley would not commit to that plan.
"I'm not sure," Trembley said. "One thing I've learned in this game is not to rule anything out. Things could change. Somebody could foul a ball of his foot tonight and be out for two or three weeks. Somebody could get hurt. That changes the whole thing. ... I don't know which way it's going to be. Even if I did, I don't think it would be fair to tip my hand and tell you."
Right-handers Brian Bass and Danys Baez were on the roster bubble as Spring Training ended, but both made the club because Eaton didn't need to be activated before making his first start. That gave the Orioles a deeper bullpen for the season's first four games.
Baez, back after missing all of last season while recovering from Tommy John ligament replacement surgery in his right elbow, tossed two scoreless innings Wednesday. Bass made his season debut Thursday afternoon, allowing five hits and five earned runs and committing a costly throwing error in two innings of work.
Eaton was signed as a Minor League free agent on March 1 after being cut loose by the Philadelphia Phillies, for whom he was 4-8 with a 5.80 ERA in 21 games in 2008.
Pete Kerzel is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.