MLB trade rumor analysis: Why might the St. Louis Cardinals be shopping for another reliever?

Since Monday when it was revealed that the St. Louis Cardinals had inquired about Adam Lind and some in the industry believe they are the frontrunners to acquire the Milwaukee Brewers' first baseman, things have been pretty quiet on the trade-rumor front for El Birdos. This is not particularly surprising since the Cardinals front office tends to keep such maneuverings close to the best. Nonetheless, The only shred of information regarding any Cardinals' trade-deadline talks came from noted MLB Twitter gossip Jon Heyman, who shared the following on Tuesday:

hear #STLCards are still looking at possible pen help, even after acquiring cishek

— Jon Heyman (@JonHeymanCBS) July 28, 2015

This on the day that the Cardinals optioned righthanded reliever Sam Tuivailala to Triple-A in order to make room on their active roster for lefthanded starter Jaime Garcia, who they activated from the disabled list. According to the indispensable Brooks Baseball, Tuivaila has averaged over 97 mph on his fastball during limited big-league action while posting an ERA for Memphis and St. Louis that masks underwhelming peripherals.The following chart contains Tuivailala's 2015 Memphis and St. Louis stats as well as his ZiPS rest-of-season projections.

This is a reliever the Cards saw fit to option out of their major-league bullpen the same day Heyman is tweeting that he is hearing the Cards are inquiring about relievers with other clubs. That's not to say there aren't other considerations. Tuivailala has options, which allows him to be sent down pain-free. He is also a young pitcher—having moved to the positions from shortstop a couple years ago—with just innings as a pro hurler under his belt. His mechanics have been uneven at times, which can contribute to control issues (check out those walk rates). Moreover, according to Rick Hummel of the St. Louis Post-Dispatch, the Cardinals instructed him to work on his cutter in Triple-A. There are plainly development reasons for Tuivailala to be pitching in Memphis rather than St. Louis.

That does not change the reality that if need be, Tuivailala is probably a serviceable major-league reliever right now. The Cardinals just don't have that need. And with Jordan Walden on a trajectory to rejoin the St. Louis bullpen, it seems like they will have the depth to avoid it. Here are the righthanded relievers currently on the Cardinals' 25-man roster and those on the 40-man but not the active big-league roster.

25-Man

• Trevor Rosenthal
• Seth Maness
• Steve Cishek
• Carlos Villanueva
• Miguel Socolovich

40-Man (but not 25-Man)

• Walden (Rehab Stint)
• Tuivailala
• Mitch Harris
• Marcus Hatley
• Matt Belisle (60-day DL)

First, it should be noted that Belisle is not actually taking up a 40-man roster spot because he is on the 60-day DL. Nonetheless, if he becomes healthy enough to pitch again in 2015, the Cards will have to clear a spot on the 40-man for him. Given the acquisition of Cishek and Heyman's tweet, it doesn't seem like the St. Louis front office is terribly optimistic that Belisle will be healthy enough to join the big-league bullpen this year.

This brings us back to Walden, who strained his biceps in his shoulder area. There was a question at the time his injury was originally diagnosed about whether he would need to undergo corrective surgery. After a second opinion, Walden opted for a more conservative rest-and-rehab approach. The Cardinals (and for that matter, we the fans) are finding out whether this course of treatment has worked. I suspect this is likely a big reason why general manager John Mozeliak may still be checking in on the asking prices for proven relievers. If Walden is unable to finish out the year healthy and pitching effectively, the Cardinals will have to use Socolovich, Tuivailala, or a pitcher similar in his level of experience and effectiveness.

Mozeliak knows his manager's tendencies. Matheny has a penchant for relying on proven relievers he trusts in late-and-close situations. The Cardinals play a lot of games that are close late. The postseason features a lot of such contests too (though a starter will likely be included in the October relief corps). Mozeliak does not want to leave Matheny with a reliever he is uncomfortable using down the stretch—such as Socolovich or Tuivailala—should the bullpen suffer another injury. He wants to avoid needing to use a roster spot on either reliever during the pennant race if it can be helped. Socolovich because he isn't very good and Tuivailala because he is still developing. Just as with Cishek, more quality arms means more fresh quality arms. Giving Matheny another viable veteran option would likely reduce the burden shouldered by other relievers.

There is also the potential that the Cardinals may need to trade away a reliever in order to acquire a player before the deadline. Thus, Mozeliak would need to make a corresponding move to restock the bullpen. His motivation in doing so would be the same as discussed above: he doesn't want Socolovich or Tuivailala to fill in such a hole.

Editor's Note: The original version of this post did not have a photo and lost some of the text I had written at the end. I apologize. I'm not sure why. I edited the post to reflect its original content and to include a picture.