PHOENIX -- Mike Baxter's rehab assignment for a separated right shoulder appears complete, and the outfielder should rejoin the Mets on Monday in San Francisco.

Baxter hit a combined .327 with eight RBIs and four walks in 57 plate appearances over three levels over the minors, including playing six games with Triple-A Buffalo. It's unlikely Baxter would start the series opener against the Giants, since the Mets are facing left-hander Madison Bumgarner.

It's clear Baxter will chip away at Jason Bay's playing time against righties, but apparently not too much initially.

Terry Collins said he wants to gauge how sharp Baxter is initially, after getting burned by Josh Thole and Bay not being sharp after activations from the DL. The difference, though, is Baxter has seen significantly more action in the minors to ready for a return.

"That's the $64,000 question," Collins said. "We've brought Josh Thole up. He got off to a rough start. We bring Jason Bay back. He gets off to a rough start. How many times do you jump on the same merry-go-round? You slot him in some spots where he might have some success. ... When he gets here, I'll see how he's swinging. But is he going to be an everyday guy? Probably not."

Baxter is likely to displace Kirk Nieuwenhuis on the roster.

• Trainer Ray Ramirez spoke with closer Frank Francisco by telephone on Sunday morning, Collins said. Francisco aborted an appearance with Double-A Binghamton, but pitched Sunday for the B-Mets. Francisco allowed a bunt single, which he fielded, but no other damage in a scoreless inning.

That may or may not be Francisco's final rehab appearance. It depends how Francisco feels when he wakes up Monday, according to the manager.

"He said he felt a lot better today," Collins said before Francisco appeared in Sunday's game. "He's going to try to pitch. So we'll see where he's at after today. ... I think the biggest thing is if he throws today, and he feels as stiff as he did the other day tomorrow, I'm not sure how much that's going to help us. I don't know if I need him back-to-back days [pitching in the minors before activation], but I do need to make sure he wakes up tomorrow feeling like he can pitch if needed."

• Johan Santana is long-tossing on flat ground and should step on a mound this week. Officially, he's on the DL with a right ankle sprain, although that contributed to shoulder weakness, team officials have suggested.

"He's said he felt great," Collins said. "The other day he did another long-toss program. Probably, most likely this week he's going to start throwing off a mound."

• On the trade deadline, Collins said he's "not really" expecting anything substantial to materialize with the Mets.

• Collins is concerned about the state of Tim Byrdak's right knee. He said Josh Edgin should get more vital usage, including some of the late-game situations in which Byrdak has been used.

As for the state of Jon Rauch's cranky knees, Collins said it is a "daily thing" going to Rauch to see how the knees are holding up to gauge whether he is available.