Why did the Cardinals choose Joe Kelly to fill the fifth starter role over Carlos Martinez?

After Sunday's spring-training game, St. Louis Cardinals manager Mike Matheny announced that righthander Joe Kelly had won the club's No. 5 starter competition "for now," tweeted KMOX Sports Director Tom Ackerman, which relegates Carlos Martinez to the big-league bullpen on opening day.

On the surface, the Cardinals' decision makes little sense because:

• Martinez has better stuff than Kelly.
• During spring training, Martinez pitched better than Kelly.
• Overall, Martinez is a better pitcher than Kelly.

So, why would St. Louis declare Kelly the winner of the spring-training fifth-starter derby?

The competition was not determined by spring training alone.

Here are the spring-training stat lines for Kelly and Martinez:

It's as plain as day that the so-called competition for the starting rotation was not based solely on spring-training performance. Nor should it have been. The idea that the Cardinals should base their decision on which player should start on something less than three starts worth of innings thrown during spring-training exhibitions against a collection of minor-leaguers and MLB regulars is absurd. The players' track records leading into 2014 appropriately played a role. So did the club's longterm plans.

The Cardinals did not base the decision on the players' respective talents.

One indicator of a pitcher's talent is stuff. And Martinez's repertoire is filthy—perhaps the best of any Cardinals pitcher. If the decision for No. 5 starter were based on stuff alone, Martinez would have won going away. But past results were also considered.

Past performance also shows that Martinez is a more-talented pitcher than Kelly. The two players' minor-league stats support this fact. Martinez's numbers have been better than Kelly's, and Martinez posted these superior numbers at younger ages.

MINOR LEAGUE STATS (CAREER)

However, this spring's competition wasn't between two players with only minor-league experience under their belts. Kelly has been a member of the MLB St. Louis staff for parts of two seasons. Martinez made one start for the Cardinals a year ago and several relief appearances. Both played roles on the postseason roster—Kelly in the rotation and Martinez in relief. How the Cardinals generally and Matheny in particular weighed Kelly's track record against Martinez's is anyone's guess. Although, the fact that Kelly has been named the No. 5 starter indicates it very well may have tipped the scales in his favor.

The Cardinals are set on managing Martinez's workload this year.

Despite Martinez being one of my favorite Cardinals prospects in years because of his thermonuclear arsenal of pitches, I was reluctant to buy into the idea that he was legitimately being considered for the opening-day rotation this spring. The reason? His light minor-league workload.

Martinez averaged more than 5 IP per appearance at just one stop in his ascent through the minors, and that was over 13 starts a season ago in Memphis. Martinez's highest innings total in a regular season was 108 IP last year. In 2012, he notched just 104 IP. Because of this, I didn't think the Cardinals would start Martinez in the big-league rotation, run his innings total from 108 to 150+ this season, and then ask for more come October should the Cards qualify for the postseason. Instead, I thought it much more likely that St. Louis would bank Martinez's innings like they did with Michael Wacha last season. St. Louis Post-Dispatch beat writer Derrick Goold confirmed my suspicions when he reported in late February that the Cardinals were likely to impose an innings cap on Martinez this season.

Matheny feels the need for an eighth-inning setup man until Jason Motte returns.

Ackerman's initial tweet of Matheny's quote that Kelly was in the rotation "for now" indicated that Martinez might yet become a starter. And Goold put some flesh on the bone of this notion in response to fan questions on Twitter (including one from VEB's very own Aaron Finkel). The Cardinals see Martinez as an eighth-inning solution until Motte is ready, but still view the righty as a starter. And the chances of Martinez joining the rotation in 2014 are "high," in Goold's opinion.

But Martinez joining the St. Louis rotation after starting the season as a reliever would mark a change in approach from what Mozeliak said in February:

The most likely pitcher to enter the season earmarked for a break at some point to conserve innings would be Carlos Martinez, the righthander. If Martinez wins a role in the rotation, Mozeliak said "he would have to be managed different." He spent last season as a starter in the minors and reliever in the majors, and the Cardinals would like to avoid a spike in innings pitched for the 22-year-old. The Cardinals also are likely to commit to a role for Martinez and not have him float from bullpen to rotation because of the difficulty of regaining stamina during the big-league season. If he returns to the eighth-inning role he had in October this season, the Cardinals would have to return him to Class AAA to build strength to start.

"It would be hard to lengthen (a pitcher) out to get him ready to start," Mozeliak said while watching Wacha and Adam Wainwright face hitters for the first time Friday. "You can’t just take a guy who has maybe stretched out in spring and think you can stretch out again in July. You have to commit. It’s a very difficult place to stretch out in the big leagues."

It will be interesting to see if the Cardinals decide to stretch Martinez out later in the season. And, if they do, how they go about doing so. Will they send him to Triple-A to gradually stretch out over a month's worth of starters or will they instead thrust him immediately into the MLB starting job?

Jaime Garcia might rejoin the Cardinals rotation this year.

If Garcia had not experienced left should inflammation, we probably wouldn't even be having a Kelly vs. Martinez debate. Back in February, the starting rotation "competition" was much more nebulously defined. Adam Wainwright was of course a lock. And it appeared Garcia was, too, if healthy. After that, no one appeared a 100% sure bet with the club openly touting Kelly and Martinez as competitors in the rotation derby. But that contest likely would've seen both Kelly and Martinez wind up in the St. Louis bullpen, with Wainwright, Garcia, Wacha, Lance Lynn, and Shelby Miller in the rotation. Now it's just Martinez joining the relief corps with Garcia starting the season not on the mound, but the disabled list.

What will the Cardinals do if Garcia is physically able to rejoin the big-league rotation this summer? Garcia threw a bullpen session over the weekend and, according to MLB.com's Jenifer Langosch, will stay in extended spring training to throw to batters before hopefully embarking on a minor-league rehab stint. If Motte and Garcia return, will that push Martinez to stretch out as a starter in Memphis, ready to join the St. Louis rotation if needed? Or, will that cement Martinez's bullpen role?

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Even after breaking down the various factors the Cardinals appear to have considered in naming Kelly to the rotation over Martinez, I'm still not sure I get the decision. Martinez is the best pitcher for the rotation right now and has ace potential. Installing Martinez in the rotation would give the Cards the best chance to win in 2014, which they are built to do. There are only so many throws in a man's arm, so why not use Martinez's in the big-league rotation right here, right now?