Aaron Cook has a 1.89 ERA in five Triple-A starts. (AP)

With a May 1 deadline looming on a major league option, Red Sox manager Bobby Valentine said Monday that if the Red Sox decide to promote righthander Aaron Cook, he will begin in the team’s bullpen. Valentine said he met with general manager Ben Cherington earlier in the day Monday to discuss a possible landing spot for him on the big league 25-man roster.

“Ben was in this afternoon,” Valentine said. “We talked again on that. I’m sure he has all his ducks in order and again, I don’t know exactly when, why, how, these deadlines and all that. Everyone’s opinion has been shared.”

If the Red Sox select him, Cook will receive $1.5 million. If they don’t he becomes an unrestricted free agent. Valentine made it clear that if the team promotes him by Tuesday, he will come out of the bullpen, despite going 3-0 with a 1.89 ERA in five starts for Pawtucket this April.

“I haven’t talked to him so I can’t speak for him,” Valentine said. “When he throws his sinker, it’s a real good pitch. A lot of hitters hit the top of it. He didn’t pitch that well [in spring training], but when he was throwing well and had that sinker, I really liked it. It’s a little different pitch than many people feature. Competitiveness, he works quickly, he fields his position, has game presence, all that good stuff. I like that, too.”

Asked about how he would manage Cook and use him out of the pen after making a series of starts for Triple-A Pawtucket to start the season, Valentine admitted he’d have his hands full.

“I think it’d be challenging,” Valentine said. “Right now, I couldn’t say it would be anything other than [relief pitching].”

Daisuke Matsuzaka is scheduled to make his next rehab start this Friday for Triple-A Pawtucket. It will be his third of the spring after starts for Class A Salem and Double-A Portland.

“Depending on the weather, we’re trying to make a plan so in case there’s bad weather, he doesn’t get off schedule,” Valentine said Monday.

Last Saturday, Matsuzaka faced 17 hitters over 4 2/3 innings, Matsuzaka allowed one run on three hits and two walks, while striking out seven (all swinging), in a game the SeaDogs won, 9-1, at Hadlock Field in Portland.

Kevin Youkilis was scratched for the second straight game with back stiffness just about an hour before the game. This is a situation that bears close monitoring by Valentine and Cherington. Valentine said three hours before the game that Youkilis was good to go after his back tightened up during batting practice on Sunday in Chicago. Youkilis apparently had a setback Monday in a similar test.

Rich Hill made his first appearance back from “Tommy John” surgery last year and recorded two outs in the eighth Sunday, allowing one hit, two walks and one earned run. Valentine said Hill’s role will come into focus the more looks he gets.

“That’s evolving,” Valentine said. “I’m not totally sure. I’m glad Rich is here. I think his rehabilitation has been miraculous. His hard work should be credited and acknowledged. How he fits back into our group and adjusts back to a mound in a big league stadium is a work in progress, I would think but I’m glad he’s here.

“Remember, that bullpen, it’s not coincidental that things look better in the bullpen since the starting pitching is pitching better. They’re all teams within teams or teams within a team.”

Marlon Byrd had a go-ahead single in the bottom of the second and a wall-ball RBI double in the fifth to raise his average to .181. That may not sound like much but when he was 3-for-43 (.070) to start his season with the Cubs, his turnaround (10-for-29, .345) has caught the eyes of many in Boston, including hitting coach Dave Magadan and Valentine.

“I’m glad he’s a Red Sox,” Valentine said. “Dave Magadan has worked with him so that he’s more comfortable at the plate than he was before he got here and I think that will continue. He’s had some good at-bats and played a good center field.

“I’m still learning about Dave. I know the guys flock to him when a new pitcher comes in. He’s religious and conscientious in his work. He’s there early and always there for the players. That’s what coaches really need to do, they need to be there. I haven’t been around for a lot of his teaching technique but it seems to work.”