More on Beckham, Peterson and injury-related notes (updated)

With tonight's postponement due to inclement weather, the Orioles likely will push back Alex Cobb to Wednesday night and Dylan Bundy to Thursday night. They could skip Chris Tillman instead of having him open the Tigers series Friday night at Camden Yards.

Confirmation on the rotation will come shortly.

Update: Cobb starts Wednesday and Bundy Thursday. It's confirmed.

The Rays will start Jake Faria on Wednesday and Chris Archer on Thursday. The latter spot had been listed as TBD.

The postponement also allows the Orioles to withhold a roster move involving third baseman Tim Beckham. He's expected to go on the disabled list before Wednesday's game, with Jace Peterson added to the 25-man roster.

Engelb Vielma no longer is needed and could go back to Triple-A Norfolk if the Orioles decide to keep Luis Sardiñas, who's out of options.

Beckham underwent an MRI this afternoon due to recurring soreness in his groin. He's also dealt with a sore Achilles, but that's not the most serious injury.

"I think the groin," said manager Buck Showalter. "He's been playing with some soreness there. Some days were good, some days were bad. Or worse. I wouldn't say 'bad.' I don't think the heel would have been DL-able. Something he'd be able to play with. But the combination of the two is the challenge."

The Orioles claimed Peterson off waivers today from the Yankees and he's headed to Baltimore.

"I just know from playing against him with New York and watching him with Atlanta and listening to our reports and things on him," Showalter said. "Played football at McNeese State, so he knows how to fall right.

"Left-handed hitter, plus-runner, has some versatility to his game, and a guy that's got some experience in the big leagues. Has a skill set that, hopefully, will play here, and something we're in need of. So, I think he's flying in late tonight and probably will fit in the picture tomorrow. That's why sometimes with the Beckham thing timing is kind of a challenge."

Most of Peterson's experience has come at second base, though he can move around the infield and play the outfield. He made an outstanding catch in left against the Orioles earlier this month at Yankee Stadium.

Second base is "where most of his reps have been over his career," Showalter said. "He can play other places, but I think he's the most comfortable there. But until I sit down and talk to him, I'm not 100 percent sure about that."

Trey Mancini will play left field on Wednesday if the weather cooperates. Otherwise, the Orioles will use him as the designated hitter.

Mark Trumbo stayed with the Orioles today while Double-A Bowie's game was postponed due to heavy rain. He could return to the Baysox on Wednesday morning to continue his rehab assignment.

Second baseman Jonathan Schoop increased baseball activities today to further test his recovery from a strained right oblique.

"Jon had another good day," Showalter said. "Jon ran yesterday, which was a big step for him. Today he's taking ground balls. We haven't gotten the return on that yet, so I'm hoping that ... and he hit off tee a little bit, so if all of that comes through well, then that will continue to move in the right direction."

The club will continue to proceed with caution and not risk a setback that could force Schoop to miss more than a month.

"It's such a slippery slope, that injury," Showalter said. "You think everything's fine and you're torqueing and doing everything, even in minor league games. There's just such a difference. A sense of exertion and effort in a major league game. It's just something different. And I've seen, I thought, really good patterns followed and there's no way anything's wrong, and then one swing puts them back at square one.

"The only thing you can go by is what he does on a minor league rehab, but that's a slippery slope. But so far we think it's on the side of a shorter one, but that could change on one swing or one move. And that's the challenge, is not getting into that area where, 'Wow, gosh, he feels great. Taking ground balls and running and (hitting) off the tee. Let's just go from A to Z overnight because of a need.' That's a mistake."

Zach Britton threw off a full mound after two half-mound sessions and his fielding drills.

"That was the next step. That went well today," Showalter said. "That slope is a big step for guys with injuries."

Britton is eligible to come off the 60-day disabled list on May 28, but it's expected to happen sometime in June. The word "early" has been used with regularity.

"I think he's got a lot of hurdles to cross," Showalter said. "Think in terms of spring training. It's like the first day of spring training today.

"I think you make a real mistake of trying to take that at a different pace than a lot of examples have shown the pace should be. We would have signed up in blood for somewhere after May 28, shortly thereafter, especially if you look at all the history of other guys, and especially what the doctors told us after they went in there and found what they ...

"There's different severities of it. They're not all the same."