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3/1/2013 6:09 P.M. ET

Battle for final rotation spot to headline rest of spring

Kelly has most experience as starter; Rosenthal, Miller also in consideration

KISSIMMEE, Fla. -- After weeks of speculating how the Cardinals' rotation may shake out by the end of the month, the club is finally at a point where it will get regular looks at each of the three young right-handers seeking the fifth spot in the rotation.

Trevor Rosenthal made his second appearance of the spring on Thursday. Shelby Miller, whose spring was briefly stalled by shoulder soreness, debuts on Saturday. And in between, Joe Kelly made his first Grapefruit League start on Friday, when the Cardinals traveled to Kissimmee to face the Astros.

Kelly's command wasn't spectacular -- 16 of the 30 pitches he threw were balls -- though that's not all that unusual for a pitcher making his first game appearance in months. Kelly worked around two walks to keep the Astros hitless and scoreless in two innings.

"The ball was coming out good," pitching coach Derek Lilliquist said. "He made some good pitches. His breaking ball was sharp. There were a lot of positives for him the first time out."

Though the Cardinals have been cryptic when unveiling their pitching plans, Lilliquist did shed some light on the team's intentions for the immediate future. For now, Lilliquist said, it will be Kelly who remains a starter in Spring Training. Miller and Rosenthal -- even though they will be built up to carry the workload of a starting pitcher -- will have to do so in relief.

Asked if the Cardinals are likely to stick with this format, Lilliquist answered, "[It] depends."

The Cardinals have not publicly revealed which of the righties is viewed internally as the early favorite to nab that final opening in the rotation. And assuming there is a correlation between Kelly's spring schedule and his positioning in that race is probably a bit premature, too.

However, the 24-year-old right-hander does come into the competition having proven more at the Major League level than both Rosenthal and Miller. Kelly made 24 appearances for St. Louis last season, including 16 starts. He notched 10 quality starts, and his 3.53 ERA ranked second best among National League rookies with at least 100 innings pitched.

"You look at what Kelly did last year when Jaime [Garcia] went down," closer Jason Motte said. "If it wasn't for him doing that, we wouldn't have been where we were last year."

In comparison, Miller and Rosenthal combined to toss 36 1/3 innings. Rosenthal never started a game, while Miller's lone start came on the final day of the regular season, after the Cardinals had wrapped up a postseason berth.

"I just am happy I'm given the chance to even get that role," said Kelly, when asked if he felt he had proven enough last year to be considered the frontrunner for a return to the rotation. "It's up for grabs, obviously. Everyone is trying their best and trying to get that job. That's what all of Spring Training is about, competing for jobs."

If there is any factor working against Kelly in this spring competition, it could actually be the value he showed last year in relief. Whereas the Cardinals have no intention of making Miller a reliever, Kelly presents more of a long-term dilemma. He was a closer in college and thrived in the bullpen last postseason.

Should need force the Cardinals to transition one of these young pitchers into a relief role, Kelly would profile as an intriguing option.

That said, he noted on Friday that his preference remains starting.

"Everyone, of course, wants to start in the big leagues," Kelly said. "That's ultimately what my goal is -- to be a starter in the big leagues."

Clarity in the competition may not come until late in March, though the Cardinals are content now simply with the fact that they can get regular looks at all three.

Rosenthal has already logged five spring innings, tied with Michael Wacha for the most among camp participants. His three-inning outing on Thursday was much improved over a spring debut in which he struggled to harness his anxiousness.

"The biggest thing with him was that he was trying to do too much and his mechanics got out of whack a little bit," Lilliquist said. "We calmed him down, told him to back off his legs and execute his pitches. He was a lot better this time out."

Miller will make his first game impression on Saturday, when he follows starter Adam Wainwright on the mound. The team's evaluators have liked what they've seen from Miller so far, both in recent side sessions and regarding his receptiveness to feedback.

It all sets up for an intriguing competition over the next four weeks. But it's a competition, Kelly said, that he won't allow himself to be swallowed by.

"I'm kind of an aloof, goofy personality. Pressure doesn't really get to me," Kelly said. "I just go out there and am just pitching again. I don't try to think about anything else out there except throwing one pitch at a time and going after all these hitters."

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.