Cole Irvin makes A’s opening day roster, Trevor Rosenthal to IL

The A’s finalized their Opening Day roster on Thursday with a couple of eye-opening moves — they have selected Cole Irvin to be the team’s No. 5 starter to begin the year and closer Trevor Rosenthal has been placed on the 10-day Injured List with a strained groin.

Irvin was one of three hurlers vying for a rotation spot vacated by Mike Fiers, who was placed on the 10-day Injured List as he recovers from hip inflammation. In Wednesday’s sim game at the Coliseum, Fiers faced off against Frankie Montas, who looks to be OK to begin the year with Oakland after dealing with a ripped fingernail in two Cactus League appearances.

Irvin beat out top pitching prospects A.J. Puk and Daulton Jefferies to make the squad. Puk and Jefferies will ostensibly be sent to the alternate site in Stockton to stay built up as starters while Irvin fills in for Fiers, who is expected to come back in the last two weeks of April.

The southpaw Irvin was acquired from the Philadelphia Phillies in a low-key cash transaction on Jan. 30. He may have won the job with his final Cactus League performance, when he hummed through six shutout innings with 10 strikeouts against the defending World Series champ Dodgers, who had an everyday lineup to begin the game.

“I know it’s just a spring training game,” A’s manager Bob Melvin said. “But when you’re coming down into the end and you’re fighting for a spot, and you run into a lineup like this and pitch in the fashion that he did, that carries a lot of weight.”

Puk and Jefferies may have better raw stuff and are homegrown first-round picks from the 2016 MLB Draft, so to see both of them optioned was a bit of a surprise. Jefferies has a better body of work throughout the minor leagues and looked fine all spring, while Puk ramped it up to four scoreless innings in his latest Cactus League start.

But Irvin showed that he might be a better pitcher than the other two — in terms of his ability to manipulate the ball in the zone and keep hitters off balance. His sinking fastball sits at about 90-92 mph and when mixed with his changeup can make him a tough at-bat. For the spring, Irvin allowed two runs in 18 innings (1.00 ERA) with a 0.72 WHIP and 18/3 strikeout/walk ratio.

Irvin has become fast friends with Jefferies this spring and A’s fans will probably like Irvin’s fun-loving attitude.

So Oakland will roll with Chris Bassitt, Jesus Luzardo, Sean Manaea, Montas and Irvin in the rotation to begin the season.

Rosenthal, the prized A’s closer free agent addition, only made four Cactus League outings after getting into game action late in camp. He pitched an inning in Monday’s contest against the Giants but clearly isn’t quite right. 

Melvin and the A’s never sounded too concerned about Rosenthal’s ability to begin the regular season with the team so this is something of a surprise as well. Eighth-inning setup man Jake Diekman figures to slot into closer’s duties for now. The southpaw with a sweeping slider didn’t allow a hit in six Cactus League innings this spring.

Rosenthal was a nice cherry on top of the A’s free agent flurry toward the end of the offseason, now the team will get to see how good it can be without their star closer. Rosenthal had 11 saves with a 1.90 ERA last season with the Kansas City Royals and San Diego Padres. 

The A’s have also selected southpaw Reymin Guduan to make the Opening Day roster after he had an impressive spring, allowing one earned run in 9.1 innings of work with a 5/1 strikeout/walk ratio.