The Dodgers knew the risks that came with acquiring talented but injury-plagued pitcher Tyler Glasnow last offseason. On Saturday, after the latest setback in his late-season elbow injury, they finally had to grapple with the worst-case scenario.

Glasnow’s season almost certainly is over because of an elbow sprain, manager Dave Roberts announced, calling it “highly unlikely” that the $136.5-million winter addition will be able to take the mound again for the Dodgers this year.

“It’s a big blow,” Roberts said. “Looking at what he meant for our ballclub, what he’s done for us, what we expected him to do, certainly there’s going to be a cost.”

When Glasnow was healthy, he performed like the ace-caliber pitcher the Dodgers were confident he could be. In 22 starts, he went 9-6 with a 3.49 earned-run average. He set career highs in innings (134) and strikeouts (168). He earned a selection to the All-Star Game for the first time in his nine-year career.

What Glasnow couldn’t do, however, was stay healthy, another injury-plagued campaign cut short after he felt discomfort in his elbow Friday warming up for a simulated game.

“I feel bad for Tyler,” Roberts said, noting that while Glasnow’s ulnar collateral ligament hasn’t been damaged, the sprain in his elbow will keep him from throwing “for a while.”

“He did everything to stay healthy and get back,” Roberts added. “It just wasn’t going to happen.”

When the Dodgers traded for Glasnow and signed him to a five-year extension, they did so understanding the risk that came with the flamethrower’s lengthy injury history.

The 31-year-old repeatedly was sidelined by elbow injuries during his time with the Tampa Bay Rays, failing to top 14 starts in a season before undergoing Tommy John surgery in 2021.

Glasnow also missed time because of other ailments, including an oblique strain at the start of last year. That’s why he hadn’t surpassed 120 innings in a season, and why, when he discussed his goals for in spring training, he said “I just wanna stay healthy … and make all my starts.”

Back then, Glasnow was optimistic that surgery had put his elbow problems behind him. The Dodgers voiced similar confidence, with president of baseball operations Andrew Friedman saying in February, “We feel like the arrow is really pointing up and that, over the next few years, he is really going to take on a lot of starts.”

Dodgers pitcher Tyler Glasnow reacts during a game against the Angels in June.

(Wally Skalij / Los Angeles Times)

“We spent a lot of time digging into that,” Friedman added then. “And that’s a bet we’re making.”

In the wake of Saturday’s news, it’s looking like a losing gamble.

Without Glasnow — who went on the injured list last month because of tendinitis and also missed time in July because of back tightness — the rotation will be down a critical piece as the playoffs near.

The Dodgers still have Jack Flaherty, their top trade deadline addition, who is 5-1 with a 2.61 ERA in seven starts with them. Last week they also welcomed $325-million offseason signing Yoshinobu Yamamoto back to the mound after he missed almost three months because of a shoulder injury.

If those two hold up over the final weeks, that still would represent a solid 1-2 punch to front the Dodgers’ potential October pitching staff.

“I’m still confident,” Roberts said. “I don’t think there’s one way to win a championship. I think you can look back at the teams recently and how their staffs came together and who stepped up for each team’s staff. So we’re going to have the guys we have, and I feel confident in whoever we run out there.”

However, the Dodgers’ rotation depth has almost completely evaporated.

Gavin Stone remains a long shot to return from his recent shoulder injury before the end of the season, though he is expected to attempt playing catch again on this road trip.

Clayton Kershaw is more likely to recover from his toe injury in the coming weeks, but he remained limited in his pregame activities Saturday, managing only what Roberts described as a “makeshift” session in the bullpen.

Walker Buehler and Bobby Miller are healthy but have struggled to find consistency after missing time because of injuries.

Rookie right-hander Landon Knack also is in the conversation for a potential postseason role, but suffered a season-worst five-run, two-inning start Friday at Atlanta.

If things truly get “crazy,” as Roberts put it, rehabbing right-hander Tony Gonsolin could enter the picture too, though the odds of that — for a pitcher who hasn’t appeared in the big leagues in more than a year — remain remote.

So what does it all mean for the Dodgers’ potential postseason pitching plans?

Most likely, Flaherty and Yamamoto anchoring the staff. And some mix of Kershaw, Buehler, Knack or Miller behind them.

That still might be manageable, especially if the star-studded lineup delivers at the plate and the bullpen can continue to carry a heavy workload.

But for a team that spent almost $500 million on remaking its pitching staff in the winter, it’s far from ideal, the calculated bet on Glasnow blowing up in predictable fashion.

“It’s certainly a hit,” Roberts said. “No doubt.”