DENVER -- As anticipated, Giants center fielder Dave Roberts went on the 15-day disabled list Thursday with an ailing left elbow and is expected to miss approximately six weeks after he undergoes arthroscopic surgery Friday.

Part of the outfield chain reaction wasn't anticipated, however: Todd Linden, who would have received increased playing time due to Roberts' departure, was designated for assignment. The Giants recalled Fred Lewis and Dan Ortmeier from Triple-A Fresno to fill their outfield contingent.

As was the case with first baseman Lance Niekro, who cleared waivers after being designated for assignment last week and was outrighted to Fresno, Linden very well could remain with the organization.

"It's a good possibility," he acknowledged, aware that the Giants have 10 days to trade him or assign him to Triple-A if he clears waivers -- although as a 26-year-old switch-hitter with a career .287 Minor League average, Linden might prompt another club to claim him.

Asked whether receiving a chance with another organization might benefit him most, Linden said, "It's kind of out of my hands right now. I'll try to make the most out of whatever situation I end up in."

Until recently, Linden's situation with the Giants appeared to be encouraging. Out of Minor League options, Linden made the Opening Day roster for the first time and impressed manager Bruce Bochy, who predicted that he would amass as many as 400 at-bats this season.

But Linden, who appeared in 30 of the Giants' first 33 games and started 12 of them, could not capitalize on his opportunities. He hit .182 with one extra-base hit and 23 strikeouts in 55 at-bats.

"Sometimes it's in the player's hands," Bochy said. "We felt like we needed to get some more production. Todd's a talented player, but he was a little lost up there at the plate. I don't know what's going to end up happening here, but he probably needs at-bats and it's hard to find them in the Major Leagues. We're not really in a position where we felt like we could wait for Todd."

"I was given opportunities. I don't know if you want to say a good one or a fair one," Linden said. "That's not my decision to make."

Wednesday against the New York Mets, Linden broke late for Jose Reyes' fly to shallow right, which fell for a single that loaded the bases and helped generate two runs that led to a 5-3 Giants loss. But Bochy said that this misplay didn't hasten Linden's banishment.

"He just had trouble making contact," Bochy said.

For Bochy, settling on the daily minimum requirement of outfielders could be a chore. Randy Winn, who will play center field and bat leadoff in Roberts' absence, is coping with a stiff back. Left fielder Barry Bonds requires periodic rest at age 42.

"You may see guys move around a little bit," said Bochy, mentioning that Pedro Feliz and Mark Sweeney could spend more time in the outfield than originally projected.

Lewis, 26, entered the mix immediately by starting in right field Thursday. He hit .263 with four home runs, 15 RBIs and seven stolen bases for Fresno, including .343 in his previous nine games. Ortmeier, 25, hit .268 with five homers and a team-high 25 RBIs for Fresno. The switch-hitter batted .176 in 24 appearances with the Giants in 2005-06.

Bochy said that Nate Schierholtz, batting .350 for Fresno, also was considered for promotion but was shaken up after a recent collision with an outfield wall.

Filling the void: Although Roberts was batting only .216, his seven steals in eight tries provided hints of his ability as an offensive catalyst.

"It's tough to lose a guy who plays the game the way Dave does," Bochy said. "He's a guy who, when he's going well, makes the club go. But we're fortunate that we have an experienced guy, Randy Winn, who has done it, so that's going to soften the blow."

Giants orthopedist Dr. Ken Akizuki will perform the surgery on Roberts to shave a bone spur and remove floating bone chips. Trainer Dave Groeschner said that the six-week estimate on Roberts' recovery could change, depending on the procedure's outcome.

Roberts followed through on his announced visit to Dr. Lewis Yocum, who confirmed that surgery would be necessary. Groeschner downplayed the suggestion that Giants management opposed Roberts' desire to undergo surgery sooner than later.

"He knew his elbow wasn't right, but he wanted to continue to play. We were trying to help him do that as best we could," Groeschner said. "We did everything we could to avoid [surgery]. We hoped we wouldn't have to do it until the end of the season. But Dave's an everyday player. You have to throw the ball a lot in center field and we just couldn't get it calmed down enough for him to play every day. We were trying to put this off until the end of the season."

Second time around: Although Tim Lincecum's fastball has drawn plenty of attention, he wants to establish his curveball, which can be equally effective, when he makes his second Major League start Friday against the Colorado Rockies.

The heralded pitching prospect estimated that he threw 80 percent fastballs in his 4 1/3-inning, five-run debut against Philadelphia last Sunday. Lincecum said that when he's thriving, he tends to throw only 55-60 percent fastballs.

"A couple of starts in Triple-A, I felt I got to the point where I could throw it any time I wanted," Lincecum said. "I want to get that back."

Coming up: The Giants and Rockies continue their series Friday at 6:05 p.m. PT. Opposing Lincecum will be Josh Fogg (1-3), who lost at San Francisco on April 30. Fogg allowed five runs in five innings that night, though only one run was earned.