"We'll get a starter from Triple-A for the 29th, which is Saturday," Orioles manager Dave Trembley said. "You guys can do the homework and figure out who that's going to be. I think that'll become self-evident in the next day or so."
Tillman, along with Jake Arrieta, has been dominant at Triple-A, securing his fifth win with six innings of one-run baseball on Monday night. In five starts in the month of May, Tillman is 3-1 with a 2.32 ERA and 26 strikeouts against seven walks. The 22-year-old right-hander will likely get the nod over Arrieta given that he is already on schedule to pitch Saturday and is on the team's 40-man roster.
Arrieta picked up his fifth win on Tuesday afternoon, allowing a run over seven innings for Norfolk to lower his ERA to an International League-leading 1.86. But it's unlikely the Orioles would ask Arrieta to make his Major League debut on short rest, and the club would also have to take someone off their 40-man in the process.
Hernandez (1-5) earned his first win of the season in his last start on Friday and would have been on track to start on Thursday. Given Monday's off-day, the Orioles can slot Brad Bergesen in for that outing on regular rest and won't need a fifth starter until Saturday.
Hernandez, who won the fifth-starter spot over Tillman in the final week of camp, was noticeably disappointed given the timing.
"You finally do get a win and then you get demoted," Hernandez said." You just take it how it is"
Hernandez, who was informed of the decision on Tuesday afternoon, said he told Trembley that he would be available for Tuesday's game if needed. Right now, his role in the bullpen is unclear, as the Orioles also called up Frank Mata and Alberto Castillo to help bolster an injury-depleted 'pen.
"What I told him and [pitching coach Rick Kranitz] told him this afternoon was 'be ready for anything,'" Trembley said. "That meant he could come in in a long role, that meant he could come in in the 7th inning and pitch one inning. I'm not so sure the best thing would be to put him in in the ninth, but I wouldn't be opposed to it."
Hernandez struck out four in his only career relief appearance, tossing 2 2/3 scoreless innings on June 6, 2009 at Oakland. Given that his fastball can reach the mid-90s, Hernandez has often projected as a future bullpen guy. As a starter, Hernandez has only pitched in the seventh inning four times in his career, tossing six full innings 10 times in 27 career starts.
Hernandez's career ERA from innings 1-3 is 4.91 and number that jumps over a run -- to 5.97 in innings 4-6. In his first 50 pitches, he is holding opponents to a career .254 batting average against, a number that goes up to .281 with pitches 51-75 and .306 with pitches 76-100. Those appearances are pretty even given that Hernandez has thrown at least 75 pitches in 28 games, lasting to the 76-100 range 26 times.
"I think I can be successful either way, starting or relieving," Hernandez said. "But at this point, we're really short in the bullpen. So I feel like me being in the bullpen is going to help the team. Whatever the team needs, I'll handle it."
Barring an injury, Trembley said the move is final and the team won't yank Hernandez back-and-forth this season.
"You could say [the move] was a need and a necessity, and you could also say that perhaps, the big picture, this is eventually the best thing for him," Trembley said. "I think it's a little of both."
Brittany Ghiroli is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.