SCOTTSDALE, Ariz. -- The absence of vacancies in the Giants' lineup makes their handful of available reserve roles the club's most coveted jobs this spring.

Manager Bruce Bochy has repeated that he might frequently switch personnel if he believes that a quicker or more rangy performer can help preserve a lead.

"It's going to be the type of club that you may see some more moves [from] late in the ballgame, whether it's putting a speed guy in there to steal a base or help score a run late in the ballgame or maybe even play defense," Bochy said recently. "It could play a major part in our decision-making."

Given the documented concerns about the Giants' prospective defense, the plethora of substitutes who will flood exhibition games, beginning with Wednesday's Cactus League opener against Seattle, would be well-advised to display decent range and a strong arm.

The flexibility provided by Mark DeRosa, who can play the infield and outfield, and Pablo Sandoval, who's capable of playing both infield corners, could influence the composition of the Giants' bench by the end of the exhibition campaign. The club's brain trust might determine that it can carry one less player than usual at a particular position or in a certain role.

But, for now, San Francisco can be expected to keep two spare infielders and two extra outfielders -- assuming second baseman Freddy Sanchez starts the season on the 15-day disabled list and the Opening Day staff features 12 pitchers.

First baseman Travis Ishikawa and utility men Emmanuel Burriss and Kevin Frandsen will compete for the infield spots, while John Bowker, Fred Lewis, Andres Torres and Eugenio Velez are the outfield contenders.

Ishikawa, Lewis and Torres are out of Minor League options, meaning they'd have to clear waivers before they could be sent to Triple-A Fresno. History has demonstrated that being out of options has helped many players keep a big league job.

Ishikawa's currently sidelined with an injured left foot, but his ability to perform baseball-related activities while wearing a walking boot should hasten his recovery. Moreover, he hits well at AT&T Park (.349 last year), he's excellent defensively and he's the only legitimate backup to Aubrey Huff. "We're a little short on first basemen," Bochy said Monday.

Huff's reputation as a defensive liability would seem to improve Ishikawa's chances of making the team. But Huff's performance in early workouts has left some coaches willing to consider that he might not be as bad as advertised. Moreover, the Giants cherish flexibility, so they must decide whether they can afford to keep Ishikawa, who plays one position. That's why Bochy mentioned during the Winter Meetings that Ishikawa might be tested in left field.

Burriss, last year's Opening Day second baseman whose 2009 season ended prematurely with a broken toe in his left foot, has been practicing primarily at shortstop, while Frandsen has worked out mostly at second base. If either of them were to make the team, he'd be extremely vulnerable to being sent to Triple-A once Sanchez returns, because Juan Uribe would assume the "super-utility" role.

"I think it's a good idea for me to work out at shortstop and try to get that back under my belt, because I took a whole year off [from that position], mixed with starting at second and being injured," Burriss said. "Getting back to shortstop in case they need me to work there would be great."

Said Frandsen, "The best thing I can do is do is produce with the bat when asked and play solid defense when 'Boch' puts me in there. Last year I think I had only one side of that, and that was the defense."

Among the outfielders, Lewis' various skills and his .388 second-half on-base percentage from last season remain tantalizing. The spark Velez temporarily provided last year after his third recall on July 27 helps his candidacy. Bowker has more power than any of the potential reserves, and perhaps anyone on the roster. He provided a reminder of this by yanking a homer to right field in Monday's intrasquad game.

Yet Torres could have an edge over all of them, because he's most adept at handling all three outfield positions. Based on the instructions he said he received, the Giants' brain trust might agree.

"I feel pretty good on all sides," Torres said. "I've been working every day in left, center and right. They told me I'm going to be everywhere. I've been working hard."

Given the situation, that's a good idea.