Barring injury, the Orioles seem set with Jeremy Guthrie and Brad Bergesen. Rookie David Hernandez has also pitched well of late and will get a longer look in the second half. But with an injury to Koji Uehara, Baltimore is forced to juggle two roles.
Perhaps most at risk is southpaw Rich Hill, who has worked to a 3-2 record and a 7.43 ERA this season and has been removed before completing five innings in half of his 10 starts. Trembley skipped Hill's last start and will ponder the larger issue next week.
The Orioles also have to decide if Jason Berken will continue to take regular rotation turns. The rookie right-hander went 0-4 with an 8.51 ERA in five June starts, and Baltimore may get to a point where it feels Berken has had enough rope.
None of those decisions are due immediately, but the Orioles do have some interesting arms to choose from at Triple-A Norfolk. Top pitching prospect Chris Tillman has prospered this season, racking up a 7-5 record and a 2.50 ERA at Norfolk.
Tillman, who is fourth in the International League in strikeouts (88), has been treated conservatively because of his age. The 21-year-old has handled every challenge laid in front of him, though, and may make his big league debut at some point after the break.
If the Orioles decide they need to make wholesale change, they can also turn to David Pauley, who was acquired in an offseason trade with the Red Sox. Pauley has gone 6-6 with a 3.94 ERA for Norfolk and could get a chance to compete in the Majors.
Baltimore also has an interesting test case at Norfolk in the form of left-hander Troy Patton, who missed all of last season while recovering from surgery to repair a tear in his labrum. Patton went 6-2 with a 1.99 ERA at Double-A Bowie, but has run into a wall at Norfolk.
Patton, who had some big league experience with the Astros before his inclusion in the Miguel Tejada trade, has gone 1-2 with a 4.43 ERA at Norfolk. The Orioles may well decide to leave him at Norfolk, but a late promotion to the parent club isn't out of the question.
Baltimore also has Mark Hendrickson on staff, but the southpaw has shown a decided split that may determine his role. Hendrickson went 1-4 with a 6.35 ERA in seven starts, but he has turned around to go 3-0 with a 2.89 ERA in his time as a reliever.
Uehara isn't due back until late in the season, and the Orioles may well decide that they're best suited to make no moves and try to ride out the second half the way they stand. The ingredients for change are there, though, if they elect to make a move.
Spencer Fordin is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.