Red Sox move Corey Kluber to the bullpen, will keep Tanner Houck in the rotation

Corey Kluber is 2-6 with a 6.26 ERA in nine starts since being signed to a one-year, $10 million deal.Matthew J. Lee/Globe Staff

ANAHEIM, Calif. — The Red Sox have moved Opening Day starter Corey Kluber to the bullpen and will leave Tanner Houck in the rotation.

Manager Alex Cora said the Sox were waiting to see how Houck came out of his start Monday and informed Kluber Tuesday of the switch.

The veteran righthander understood the move.

“Things haven’t been up to my expectations with the team thus far,” Kluber said before the series finale against the Angels Wednesday evening. “It’s a change in role, but at the end of the day pitching is still the same. I have to continue working and find ways to improve and ways to get better.”

Kluber is 2-6 with a 6.26 ERA in nine starts since being signed to a one-year, $10 million deal. He lasted only 2 ⅓ innings against the Padres this past Sunday, walking three and allowing five runs. Kluber said he wasn’t surprised by the move, knowing that he’s underperformed.

“I know it sounds cliche but I’ve always tried to take it day by day,” he said. “I’m not trying to look too far back as [to what got me here]. I sort of break it down and go day by day. We talked about it yesterday, and now looking forward I’m just trying to figure out ways to get better.”

Houck is 3-3 with a 4.99 ERA in nine starts. He allowed one run over six innings in a 2-1 loss to the Angels Monday. Cora said Monday that Houck was one of the team’s best starters and reiterated that Tuesday, adding that from a stuff perspective, Houck has the potential to be dominant and believes the righthander is trending in the right direction.

“Tanner is throwing the ball well,” Cora said. “After talking to [Corey] he knows right now those guys deserve to start. We’re going to keep working with him, get him better and help him.”

Kluber, 37, pitched once in relief in the playoffs for the Rays last season. His last regular-season game as a reliever was in 2013. Despite the inexperience in that role, which Cora said will involve Kluber going multiple innings, pitching is still pitching to the righthander. The veteran even noted that he will lean on some of his younger teammates who have had to shuffle between the bullpen and the starting rotation in the midst of a season.

“I think that there are definitely things routine-wise that will be a little bit different,” Kluber admitted. “But I’ll have conversations with guys like Tanner and Garrett [Whitlock], who have bounced back and forth a little bit before. I’ve got former teammates who have done the same thing and I’ll pick their brains about maybe what did or didn’t work. I’m not trying to make it this daunting thing. At the end of the day when the adrenaline hits and it’s your turn to pitch, I feel like as long as I prepare myself for it then I’ll be fine.”

Rotation coming into focus

With Nick Pivetta and Kluber now out of the mix, the Sox’ five-man rotation (in order) is as follows: James Paxton, Chris Sale, Whitlock, Houck, and Brayan Bello. The six-man rotation benefitted Sale and Paxton, but the upcoming off days Thursday and Monday would have been too much rest in between starts for the entire rotation.

Paxton and Sale haven’t experienced a five-man rotation this year and Cora noted that the team will have to be cautious with the pair given their injury history. However, the manager is confident the lefthanders will adjust and perform despite missing that extra day of rest.

Paxton got the start Wednesday night against the Halos.Ronald Martinez/Getty

“I think we’re in a stage with Paxton and Chris that they went through the repetitions,” Cora said. “In the case of Paxton, he pitched on regular rest like four or five times. It’s time to go. They haven’t pitched in a while. I know they want to pitch, so we’ll see where it takes us. Hopefully they can stay healthy.”

The Sox bullpen now features four multi-inning guys in Kluber, Nick Pivetta, Josh Winckowski, and Kutter Crawford.

“We’re in a good spot in the bullpen,” Cora said.

Mayer delivers

Marcelo Mayer achieved a career milestone Tuesday. Could another soon be close at hand?

The top-ranked Red Sox prospect, a 2021 first-round pick (No. 4 overall) out of Eastlake High School in San Diego, drilled a pair of homers for the High A Greenville Drive in Rome, Ga., against Atlanta’s affiliate. It was the first multi-homer game of Mayer’s professional career.

Mayer’s first blast was an opposite-field shot to left that left the bat at 98 m.p.h. His second was pulled down the right-field line with an exit velocity of 105.

“To hit one down the left-field line and then to hit one down the right-field line was pretty impressive,” said Red Sox director of hitting development Jason Ochart. “The guy has shown a really impressive ability to just hit.

“He’s got power, but he’s also just a good hitter. He can use the whole field, he can battle with two strikes, he understands the situation. I’ve just been really impressed with how advanced he is as a hitter.”

Mayer is hitting a robust .312/.387/.576 with 7 homers and 18 extra-base hits in 30 games with Greenville. Though one of the youngest players in the South Atlantic League, the 20-year-old shortstop ranks among the league leaders in batting average (seventh), on-base percentage (15th), and slugging (fifth). In 13 games in May, he’s leading the league in homers (6), RBIs (18), slugging (.793), and OPS (1.196).

Mayer also has shown evidence of year-over-year development. He’s hitting the ball harder than he did a year ago, has cut down slightly on his strikeout rate, is hitting fewer ground balls, and is barreling the ball more frequently to the pull side.

His performance raises questions about whether Mayer might soon move up to Double A Portland. The Sox acknowledge that he is building an impressive case.

“You want players to force your hand [on promotions],” farm director Brian Abraham said in mid-May. “You want players to force those conversations.

“He does a lot of things really well, he works hard, he’s mature, has good baseball intellect, he’s a good teammate, he does all the things on the subjective side you’d hope to see. No doubt he’s knocking on the door. He’s pushing down the door. And he’s consistent. That’s what we want to see.”