SAN FRANCISCO -- By far, the toughest roster cuts the A's still must make are in their overloaded bullpen, where it appears there are five pitchers vying for just one remaining spot.

Oakland almost certainly will go with seven relievers, and six spots would appear sewn up: right-handers Grant Balfour, Ryan Cook, Chris Resop and Pat Neshek and left-handers Sean Doolittle and Jerry Blevins.

Manager Bob Melvin hinted Thursday night at AT&T Park that the final spot will go to somebody who can give Oakland multiple innings, and while left-hander Travis Blackley would appear the most obvious candidate, he has had a poor spring (27 hits in 12 2/3 innings, 14.21 ERA).

Moreover, Melvin named four other pitchers who are viable long-man candidates -- left-handers Jordan Norberto and Pedro Figueroa and right-handers Evan Scribner and Mike Ekstrom.

"It's a good problem to have, but there are probably going to be a few guys who deserve to make the team that don't," Melvin said. "There's usually a couple guys where that's the case, but probably a few more this year based on the depth we have in the bullpen. The last few cuts will be difficult."

Norberto, Scribner and Figueroa all have minor league options available, while Ekstrom is a nonroster pitcher signed to a minor league contract. The manager said options certainly could play a factor, but not necessarily.

"There are three games left and it might come down to some performances these last three days," said Melvin.

There are a lot of variables. Despite his poor spring, Blackley was valuable starting and relieving last season and Melvin maintained that would be weighed. Norberto, meanwhile, was very good in 2012 until going down in mid-August with a shoulder injury. But he, too, has had a so-so spring.

Ekstrom has had the best spring numbers of the group. He pitched 15 innings over 10 games and posted a 1.20 ERA.

  • Shortstop Hiroyuki Nakajima, still nursing an injured left hamstring, will not play in any of the Bay Bridge Series games. He was scheduled to be evaluated by A's team doctors during the game to determine a future course.

    Nakajima injured his hamstring Tuesday running to second base, only moments after snapping an 0-for-22 slump with a single. Considering he will not have played in nearly a week by Opening Day, it's likely the Japanese shortstop will either start the season on the disabled list or in Triple-A.

  • Right-handed reliever Fernando Rodriguez had successful Tommy John surgery on his elbow. Rodriguez, acquired from Houston along with Jed Lowrie, pitched in just four games and 2 2/3 innings this spring before his elbow gave out.

    "From what I hear, everything went really well," Melvin said of the surgery.

  • Closer Grant Balfour said that despite just four spring outings, one of those in a minor league game, he's ready for Opening Day. Balfour got off to a late spring start due to a torn meniscus in his knee that required surgery.

    Balfour added that the last phase of being fully ready is not so much pitching, but fielding bunts and covering first base, which he has been working on the past several days.