Who will be sent down when Mitchell Boggs returns for the Cardinals?

From all appearances, Mitchell Boggs' stay in the minors will not be a long one.  Sent down on May 3rd to work on his mechanics (and get his confidence back), Boggs seems to be doing just that.  So far he has pitched 5 innings without allowing a run.

Thus, it probably won't be long before the Cardinals call on him again.  He's just too good of a pitcher to leave in the minors.

But, when he's called back up, who will the Cardinals send down?

Here are 3 most likely possibilities:

Joe Kelly

Kelly has struggled so far this year, posting a 7.11 ERA in 12.2 innings.  Part of the problem may be that he doesn't appear to have a clearly defined role.  After starting the season as the long man in the pen, he was rarely used, in part due to the success of the Cardinals starters.  Mike Matheny has tried him in other spots, but his use has been sporadic.

In addition, after starting the spring as a candidate for the 5th starter spot, it appears that he was not considered to fill in while Jake Westbrook is on the shelf. 

Perhaps the Cards could send him back to AAA to stretch him out in case Westbrook's injury takes longer to heal and/or John Gast can't fill the gap (although he seemed pretty good last night).

Carlos Martinez

After visa issues delayed the start of his season, Martinez made just 3 starts for AA Springfield before he was called up to help shore up the Cardinals pen.  Despite one rough outing, in which he gave up 3 runs in 0.2 innings, Martinez has looked pretty good. 

However, when Boggs comes back, the Cardinals may no longer need Martinez' power arm in the bullpen and could send him back to AA to continue his development as a starter.

Seth Maness

Maness has been pretty impressive since joining the Cards pen, throwing 4.1 shutout innings while allowing only one hit.  A control pitcher, he pitches to contact and has an impressive 10.0 GO/AO ratio (i.e. he's inducing a lot of groundouts).  He has even added two vulture wins to boot.

Maness appears to be filling the long reliever role that Kelly was suppose to fill. 

However, despite his success, the Cardinals could still return him to the minors to stretch him out as a starter in case another need arises.

Prediction

My feeling is that the promotion of Martinez and Maness was only suppose to be a temporary thing until Boggs got his head on straight.  Thus, I predict that Martinez will be sent down once Boggs returns.  Martinez needs to continue to develop as a starter and keeping him in the majors this year will only delay that development.

Of course, the Cardinals will likely face this issue again when (or if) they feel Marc Rzepczynski is ready to return.  Based on their performances so far, I think the Cards would likely keep Maness over Kelly, as Seth has been the more effective pitcher.  But that could change by the time "Scrabble" is deemed ready.