With spring training fast approaching, Doug Padilla previews the White Sox roster by position.

The White Sox considered the bullpen an area of strength so they shipped off right-handers Jason Frasor and Sergio Santos in offseason trades to save a little cash and strengthen the farm system.

But the Santos move leaves the White Sox with one of their biggest challenges of the spring: Finding a closer.

The Opening Day closer job appears to be down to Matt Thornton or Jesse Crain. The lefty Thornton looked uncomfortable in the role to start the 2011 season. The righty Crain, meanwhile, was solid in a setup role before running out of gas late in the season.

Young right-hander Addison Reed can’t fill two bullpen roles, but his emergence last season was part of the reason Frasor and Santos were dealt. When the season starts, Reed figures to be used like Frasor was when he came over at midseason in a trade with the Blue Jays. Eventually, though, he will be aimed for the closer role, whether it’s later in 2012 or beyond.

Veteran Will Ohman will be the only other lefty in the bullpen other than Thornton, unless Hector Santiago can earn his way onto the club with a solid spring. Dylan Axelrod and Zach Stewart are expected to duel for a long-man role, a spot not utilized much last season since a six-man rotation was used for a long stretch.

Brian Bruney will get a chance to earn a spot back on the roster after he was invited to camp on a minor-league deal. Even the deal that sent Ozzie Guillen to the Miami Marlins could pay dividends for the relief corps. Part of the compensation the White Sox received for Guillen, right-hander Jhan Marinez, has an outside chance at a bullpen spot.

BEST-CASE SCENARIO IN 2012: A spirited spring duel lands Crain with the closer job meaning the lefty Thornton and the righty Reed can set up. If Bruney is able to handle a sizeable workload in middle relief everybody can settle into their roles nicely, allowing Ohman to take on a lefty specialist job. A real assist could come from a minor leaguer like Gregory Infante, or future starters Nestor Molina or Simon Castro stepping up to land a relief role.

WORST-CASE SCENARIO IN 2012: The White Sox don’t appear to have as many options at closer as they did last season, so if Thornton or Crain aren’t up for the job it would spell trouble. Would the White Sox dare push Reed into the role with limited big-league experience? The White Sox need the Thornton/Crain closer battle to be epic and ultimately a tough decision since the pitcher that isn’t asked to close will still be needed in key late-inning spots as the setup man.

KID TO WATCH: Clearly this is Reed, but he is virtually guaranteed a roster spot so we’ll dig a little deeper here. Santiago was impressive every step of the way last season. He had 5 1/3 scoreless relief innings in the big leagues while still posting a 3.60 ERA in 23 starts at two separate minor-league levels. His chances of making the White Sox’s bullpen would seem to center around Thornton winning the closer role since using three lefties in relief to get to the closer, like the White Sox did last season, isn’t ideal.