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6/22/2014 4:51 P.M. ET

Buchholz plans on being less predictable

OAKLAND -- Clay Buchholz had a rough first two months of the season before going on the disabled list with a hyperextended left knee, but he will return to the Red Sox with increased confidence in his pitches, ready for a fresh start.

"I'm 100 percent," Buchholz said on Sunday. "Knee is a non-issue, and it's just a matter of getting back out there and getting re-acclimated with pitching at this level."

In 10 starts this year, Buchholz has gone 2-4 with a 7.02 ERA. Part of the problem, he explained, was that he'd become too predictable.

"The two pitches I felt comfortable throwing was fastball and cutter, and that's basically all I threw," he said. "That's one of the reasons I was getting hit."

During his rehab, Buchholz worked on "pitching backwards" -- throwing offspeed stuff early in counts.

"I've always been a guy to throw curveballs or changeups first pitch, and throughout this whole season it's been fastball-cutter for me," he said. "I feel like, if I can switch it up and throw one of four or five pitches first pitch, I'll have a better chance of success, rather than just throwing one of two pitches."

In his final rehab start on Thursday, Buchholz tossed six shutout innings.

"This is like start over for me," he said. "I'm not worried about the numbers or anything; there's nothing I can do to change them, except by going out and pitching well."

Buchholz is a likely candidate to start the Red Sox's series finale in Seattle on Wednesday.

Rotation decision coming soon for Red Sox

OAKLAND -- Several big roster decisions are looming for the Red Sox, but they do not expect to make a move until Wednesday, a day for which they have yet to name their starting pitcher.

"We're not looking to do something prior to Wednesday," said manager John Farrell before Sunday's series finale against the A's.

The most likely scenario seems to be that the team would activate right-hander Clay Buchholz from the disabled list to face the Mariners. Buchholz was with the Red Sox in Oakland and made his final rehab start Thursday after recovering from a hyperextended left knee.

"Clay is certainly a candidate, but we recognize fully that we've got to make a roster move to get him back active to us," Farrell said. "We know that when Clay comes to us, it's going to be in exchange for another pitcher.

"We get another day further, our pitching plans will start to become a little bit more clear."

If Buchholz does get the nod, Rubby De La Rosa could be the odd man out, although he made a strong case to stick around with seven innings of one-run ball on Saturday.

De La Rosa has options remaining, as does Brandon Workman, who is eligible to return from a six-game suspension on Tuesday. But Farrell has expressed his desire to keep Workman in the rotation.

With Jon Lester, John Lackey and Jake Peavy occupying three rotation spots, just two remain for Buchholz, Workman, De La Rosa and Felix Doubront. Doubront returned from the DL on Friday and is out of options.

For the moment, the Sox are content to stand pat until Wednesday, despite currently having only three available bench players.

"[On Wednesday] we would get back to ideally our normal allotment of pitchers and position players," Farrell said.

Worth noting

• Shane Victorino (right hamstring strain) returned to Boston for treatment and took batting practice in Lowell, Mass., on Sunday. Farrell is now eyeing New York, not Seattle, for Victorino's potential return.

• Farrell said that Red Sox hitting coach Greg Colbrunn -- who was hospitalized June 4 with a brain hemorrhage -- is "improving" and is "back to more everyday activity day by day.

"We know it's going to be a little while yet," said Farrell. "It would be encouraging and yet somewhat [surprising] if he returned before the All-Star break."

Aaron Leibowitz is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.