"Olson will start tomorrow. I've gotten medical clearance to activate Jones," Trembley said. "The rest of the callups, I'll talk to [president of baseball operations] Andy MacPhail about after the game tonight, and we'll take care of that tomorrow."
Baltimore is also expected to purchase the contract of right-handed reliever Jim Miller from Norfolk before Monday's game.
Jones, who has missed most of August with a fractured left foot, has been itching to go for quite some time, but the Orioles wanted to make sure he could run full-speed and take batting practice before they rushed him back into action. Olson, meanwhile, was sent back to Norfolk to rebuild his confidence and to get back in a groove from the starting rubber.
The southpaw had worked to a 7.90 ERA since the All-Star break, and he'd notched an ERA over 8.00 in both July and August. But the Orioles haven't had much luck filling the rotation in his absence, so Olson's back for good.
"What I hoped he learned from it is you've got to command your fastball," said Trembley. "You've got to throw it over the plate. You've got to pitch ahead. He'll get an opportunity tomorrow to pitch at Fenway Park, and we'll see what we've got."
Olson (8-6, 6.38 ERA) will have to finish strong to get the Orioles to earmark a rotation slot for him next season. The 24-year-old is indicative of a larger trend in Baltimore's organization with younger pitchers that have demonstrated that they're good enough for Triple-A without really claiming a spot on the big league staff.
Radhames Liz also fits in that category, as does Brian Burres. The Orioles may not have more than two rotation slots spoken for next season -- those of Jeremy Guthrie and Daniel Cabrera -- and will be looking for someone to step up. Trembley wasn't comfortable looking that far ahead, but he acknowledged that he needs to see more out of Olson.
"I would think that every opportunity he gets is a big one," he said. "I'm not looking for him to be perfect. We're just looking for improvement. We're looking for him to be somewhat more consistent, get us deeper in the game, command the fastball."
Then again, said Trembley, you can take that same lesson plan to virtually every pitcher on his staff.
"It all goes back to square one with us. We've been saying it about every guy," he said. "If you cannot command the fastball, you cannot have any type of success at this level. If you can't hit the fastball, you're probably not going to have much success as a position player. I'll put it right to the point. I think guys make it a whole lot more difficult than it is.
"You've got a chance if you throw it over the plate. You have no chance at all if you keep walking people and pitching behind. It's only a matter of time before you're going to get yourself in a situation where you're going to get your team behind, you're going to get yourself in trouble and you're going to get taken out of the game."
Spencer Fordin is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.