WEST SACRAMENTO, Calif. — Even on good days, there’s still bad news.

A few hours after activating Ramón Laureano off the injured list, Orioles interim manager Tony Mansolino announced that first baseman Ryan Mountcastle was diagnosed with a Grade 2 hamstring strain and will miss between eight to 12 weeks.

“We love Mounty, he’s a huge piece of this for us,” Mansolino said before Friday night’s series opener against the Athletics. “He’ll be back at some point. It’s incredibly disappointing. I feel for him, the group feels for him, but we’ve got to move forward. We’ve got some good players here that will step up and pick up the slack.”

Mountcastle suffered the hamstring injury while racing home on a double steal last Friday in the Orioles’ 2-1 victory over the Chicago White Sox, the game that began Baltimore’s six-game winning streak. The 28-year-old was hitting .246 with a .628 OPS before the injury, though he was one of the club’s best hitters in May with a .298 average and .714 OPS.

His injury could present the first legitimate opportunity for regular playing for prospect Coby Mayo. He was recalled after Mountcastle was placed on the IL and has started five of the past six games, including two at first base, a position Mayo is still learning.

“He’s been in there almost every day,” Mansolino said. “He’s getting an opportunity. There’s a lot that goes into playing there. We ultimately have to write the lineup to win the game that night. Our goal right now is we’re trying to win games every night. That’s what frames the decision on who plays and who doesn’t.”

Mayo, the Orioles’ No. 2 prospect, has struggled in sporadic playing time in the majors after making his MLB debut last season.

He’s a career .118 hitter with a .343 OPS in only 76 plate appearances, but he was one of the best power bats in the minor leagues with a career .885 OPS in Triple-A. Mayo, 23, is 3-for-15 with a walk and his first extra-base hit, a double on Friday night, since he was recalled last week.

Mountcastle’s injury could also impact the Orioles’ trade deadline. While they won six straight games before losing Friday night’s opener, 5-4, their odds of reaching the postseason are still minuscule, which makes it possible they’ll sell at the deadline. One player who’s long been hypothesized to be on the trading block is Mountcastle, who will be a free agent after the 2026 season.

While players on the IL can be traded, it’s unlikely given the complications of such moves. Mountcastle’s timeline puts his return likely in August, but it has the potential to drag into early September.

Laureano is the latest injured player to rejoin Baltimore after Colton Cowser did so Tuesday, but Mountcastle is among 10 players on the Orioles’ IL: Jordan Westburg, Gary Sánchez, Tyler O’Neill, Cedric Mullins, Kyle Bradish, Grayson Rodriguez, Tyler Wells, Albert Suárez and Cody Poteet. Most of the position players are nearing returns, while Mountcastle and the pitchers are still weeks or months away.

Sánchez (wrist inflammation), Westburg (hamstring strain) and O’Neill (shoulder impingement) are on minor league rehabilitation assignments and could be back next week. Mansolino said that Westburg is the “most likely one to be there Tuesday” when the Orioles return home to face the Detroit Tigers. Westburg, an All-Star in 2024, has missed the past six weeks with his injury.

Mansolino said the club wants the rehabbing players to get comfortable at the plate before returning to the majors.

“We need them to get their at-bats and get going,” he said.

Have a news tip? Contact Jacob Calvin Meyer at jameyer @baltsun.com, 410-332-6200 and x.com/JCalvinMeyer.