PEORIA, Ariz. -- The Mariners made a pair of roster moves Monday to bring their active roster to 28, and with another pair of injured list designations imminent, the 26-man roster has some clarity, if not finality.

“Our roster is set, so we will go forward with that,” manager Scott Servais said before the Spring Training finale with the Padres. "Certainly, the last few conversations are always a little bit more challenging. Guys that had really good springs that didn't make our team, but I think those guys know how we feel about them, and they will play a big role at some point throughout the season. They just have to wait their turn a little bit.”

Right-handed pitcher Justin Topa was optioned to Triple-A Tacoma and infielder Mason McCoy was reassigned to Minor League camp Monday. And though it’s not official yet, the Mariners are expected to place outfielders Dylan Moore (oblique strain) and Taylor Trammell (broken hamate in right hand) on the IL to start the season.

“I thought Topa had a great spring,” Servais said of the 32-year-old righty with 17 appearances under his belt, all from the last three seasons in Milwaukee. “Both Topa and Gabe Speier really stood out for me in the spring, and Riley O'Brien as well. Topa and Speier separated themselves and pitched good enough to make our club.

“Both those guys are really good people,” Servais added. “They believe in the things that we've thrown at them. They've taken that and put it in play in their outings in Spring Training, and they've gotten very good results. It's all trending in the right direction, other than the fact that they won't be with us when we open.”

The biggest challenge for Topa and Speier was to break into a bullpen that had nearly all its arms returning from last season.

“Those guys have earned the right to continue to do their job down there, and we'll give them the ball and go from there,” Servais said of his returning relievers.

Reassigning McCoy, who has spent the vast majority of his Minor League career at shortstop, leaves the Mariners without an obvious replacement for J.P. Crawford, but Crawford should be healthy and in the Opening Day lineup at short, and he’s not expected to miss many starts, at least early on.

“J.P. is going to be fine,” Servais said of the time Crawford has spent down since taking a foul ball off his right foot Friday. “He'll go through the workout Wednesday in Seattle. He's going to be fine and no issues there. We do have off-days built in, you know about one a week through April, which helps.”

Sam Haggerty will likely see some time at short in his super-utility role.

“Sam’s going to play all over the place, and that's one of the things that we wanted to focus on this spring is get him some reps in center field, a few reps at first base,” Servais said. “The middle infield is where you'll see him most of the time. He'll get some starts at second. I don't know how many starts he'll get it at short. Probably not a lot. But he's a guy that you can fill in if something happens. If one of those middle infielders is going to be out -- for maybe not an IL, but maybe he's out four or five days -- then we may have to shuffle our roster a little bit and we may have to bring out a middle-infielder type from Tacoma.”

Servais was optimistic that Moore may return to the team earlier than initially expected, projecting a mid-April reunion at the latest.

In a final effort to assess his roster’s versatility, Servais has been getting Tommy La Stella a couple late looks at third base. La Stella started at the hot corner Sunday against the Padres and was slated for another start in a “B” game Monday morning.

“We've got Eugenio Suárez, we've got [Haggerty] at third as well, so we've got coverage there, but I wanted to get him out there and see what that looks like,” Servais said of La Stella. “Tommy's always been an offensive player. But if you've got to fill in late in the game or something, I just want to make sure he's capable of doing that.”

Ultimately, the team heads home in good health, with enough depth to have options, and the talent to contend.

“We're in a good spot,” Servais summed up before the journey north.