Why not a Michael Wacha-Carlos Martinez piggyback tandem in the starting rotation?

When Michael Wacha starts on Sunday for the Double-A Springfield Cardinals, the righty will take another step in his journey back from a rare injury that so rudely interrupted his second MLB season—but he's still several steps away from returning to St. Louis. As Derrick Goold reported in the St. Louis Post-Dispatch, last week's simulated game put Wacha's workload at a level on par with the first or second week of March. Brian Stull of St. Louis Baseball Weekly shared that general manager John Mozeliak stated that Wacha will be on a pitch limit of 35 or 40 in his first live game action since June 17. If Wacha's shoulder responds positively to those forty or so pitches, the Cardinals must figure out what the next step will be in attempting to build up the 2013 NLCS MVP's arm strength so that he can join the St. Louis pitching staff down the pennant race's home stretch.

Springfield's season will end on Labor Day with too few wins to qualify for the postseason, so Wacha can't make a second start with a higher pitch limit in Double-A during his rehab stint. The possibilities include Wacha joining one of the organization's playoff-bound affiliates for another start or him pitching a simulated game in St. Louis, but nothing is definite. Also unclear is whether Wacha will be able to build up enough arm strength to throw 90+ pitches every fifth day before the calendar turns to October.

With Justin Masterson's rotation spot an open question due to ineffectiveness and Shelby Miller's sophomore season going so badly that he is tinkering with a new pitch in late August, the Cardinals may have need for a rotation upgrade. Even if Wacha isn't able to build up the strength necessary to shoulder a typical starter's innings total, the Cardinals should nonetheless install him in rotation—with Carlos Martinez, as a piggyback tandem.

Derrick Goold and Bernie Miklasz discussed the possibility of pairing Wacha with a reliever in the latest episode of The Best Podcast in Baseball (their podcast, which I cannot recommend highly enough to Cardinals fans) and I loved the idea. The notion of injecting piggyback starters into a major-league rotation has intrigued me since the Cardinals implemented a tandem system with its minor-league affiliates under Jeff Luhnow. The Cardinals long ago abandoned the practice, but the idea of such a radical change to how clubs deploy their pitching staffs has stuck with me for two primary reasons: effectiveness and health.

Effectiveness

Pitcher effectiveness adds further support to such an arrangement. Overall, pitchers are most effective the first time through the lineup and become less effective each subsequent time through. During the offseason, I looked at this reality in examining what trends influence the removal of a starting pitcher. Here are the 2013 MLB-wide splits for pitchers based on times through the batting order:

Not surprisingly, this trend has continued through the first five months of this season.

Health

After taking over as general manager of the Houston Astros, Luhnow resurrected the tandem pitching system, implementing it in the organization's low minors. This year, the Astros expanded the practice so that all of the club's minor-league affiliates—all the way up to Triple-A—are using it. Luhnow explained the primary reason why the Astros decided to expand use of the tandem system to Brian T. Smith of the Houston Chronicle, stating:

"It worked very well. It’s anecdotal. But we found pitchers were healthier and we suffered very few injuries as a result of this."

Given the questions still surrounding Wacha's short- and long-term shoulder health, pairing him in tandem with another pitcher would be a good fit for the end of the 2014 season (if not beyond). Throw in the Cards' yo-yoing of Martinez between the bullpen and rotation as well as between St. Louis and Memphis in addition Matheny's usage of the young Dominican with thermonuclear stuff, and you have a perfect tag-teammate for Wacha. What's more, the number of arms in the relief corps that comes with the expanded September roster makes such an experiment all the more palatable. The Cardinals should not be afraid to get creative with the rotation and pencil in Wacha-Martinez every fifth day.