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3/10/2013 5:28 P.M. ET

Questions remain for Cards with three weeks left

JUPITER, Fla. -- Monday marks the halfway point of the Cardinals' 32-game Grapefruit League slate. It also puts the club exactly three weeks away from its season opener, in Arizona.

Nearly four weeks deep into camp, not much has actually been settled. Roster competitions remain, though some in contention for those spots have made strong early statements.

Rafael Furcal's decision to have elbow surgery answered one of the bigger questions facing the Cardinals this spring. Here are five of the biggest remaining questions that await similar clarity:

1. Who will the Cardinals anoint as their fifth starter?

The competition is down to two -- Joe Kelly and Shelby Miller -- after the Cardinals made the decision last week to begin transitioning Trevor Rosenthal into a relief role. Both Kelly and Miller have made two spring appearances, and each seems guaranteed to make at least one more before the Cardinals come to a decision.

Miller, after moving past soreness in his shoulder, has looked the steadier of the two. He's pitched aggressively and used his offspeed pitches with less hesitancy, and is clearly benefiting from the strength he added over the winter.

Working in Kelly's favor is the resume he built as a starter last year. Of the 16 starts he made, 10 were quality ones. The command problems he's had early in spring appear to be the result of some anxiousness to prove he's deserving of a rotation spot.

And through it all, the two have been Spring Training roommates.

"We're still really good friends and hang out all the time," Miller said. "We both know what's at stake. We're just doing what we always do -- acting like we're both starters."

2. How will playing time be divvied up at second base?

Now that the Cardinals are comfortable using Matt Carpenter as a second baseman, they have to decide how often they will. Carpenter and Daniel Descalso continue to split spring playing time at the position as the Cardinals weigh the options for the regular season.

"They've both done everything we had hoped for," manager Mike Matheny said. "We still have a lot of time to see how that plays out."

Descalso, the stronger of the two defensively, started 66 games at second last season. His bat is more in question, though he has made a positioning adjustment that he hopes will lead to more consistent production.

Carpenter has shown no obvious signs of being in over his head at second, a position for which he was tutored throughout the offseason. Carpenter, who can also make spot starts at four other positions, brings an impressive offensive pedigree to the mix.

3. What will the Cardinals do with Matt Adams?

Despite bashing his way through the Minors the last few years, Adams came to Spring Training seemingly without a place to fit on a Major League roster that has three other first baseman -- Allen Craig, Carpenter and Ty Wigginton. But with a terrific showing, Adams has pushed his way into serious conversations for a bench spot.

"The thing that I can control is getting my work in and coming to the ballpark each day and wanting to learn and get better," Adams said. "Whatever they do with me -- whether it's send me to Triple-A, keep me with the Cardinals or whatever -- I'll be ready."

What will likely determine Adams' Opening Day fate is whether the Cardinals opt to keep two shortstops on the roster. There is a scenario in which St. Louis could get by with only one. In that case, Descalso would serve as a backup.

If he breaks the big league roster, Adams would give the Cardinals a left-handed power threat off the bench. Last year he hit 22 doubles and 18 homers in 67 Triple-A games.

4. Will the injury to Marc Rzepczynski's eye create space for another reliever?

The Cardinals should know within the next few days if a seemingly innocuous trip to the golf course will jeopardize Rzepczynski's availability for the start of the season. It is believed that while taking his second swing of the day on Friday, Rzepczynski knocked a piece of debris into his left eye.

Rzepczynski has been on bed rest since the incident and is scheduled for a followup with an eye doctor on Monday. The Cardinals don't anticipate any long-term impact to Rzepczynski's vision, but when he can get back on the mound remains unknown.

"I understand that things happen," Matheny said. "We're just still at a point right now where we're hoping that everything clears up and that it checks out OK."

If Rzepczynski doesn't have enough time to prepare for the season, the Cardinals will likely begin the year with one lefty in the bullpen. Several relievers could sneak into consideration for a bullpen spot that wasn't expected to be up for grabs.

5. Will surgery fix Matheny's back?

Following Sunday's 3-0 loss to the Mets, Matheny returned to St. Louis, and he will undergo surgery on his back on Monday. His hope is that he's back in the dugout on Thursday and can move past the pain and numbness that has been affecting him this spring.

Addressing the pain and missing only two games would be among the best-case scenarios for Matheny, who initially feared the potential of a longer layoff. If the surgery does not completely relieve the discomfort, though, he will consider additional options. That would not be ideal for the Cardinals, who would have to start considering the possibility that Matheny will be absent during the regular season.

Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.