Who will be the next top prospect to get the call for the Cardinals?

A little over a month into the season, the Cardinals have already had to call upon their deep minor league talent to help out at the major league level.  The Cards recently called up Carlos Martinez (#3 on the Cardinals prospect list, per Baseball America) and Seth Maness (#23) to help shore up their bullpen. 

Who of the Cardinals top prospects might we see next?  There are several options to consider.

John Gast

Gast has been dealing at AAA Memphis.  The former 6th round pick has allowed just one earned run in 34.2 IP.  He may not have the stuff of some of the Cardinals other top pitching prospects, but he seems to know how to make the best of what he's got.  Gast could get the call should one of the Cards starters go down with an injury.

Michael Wacha

After a dominating spring with the Cardinals, Wacha has continued to impress with a 1.82 ERA in 34.2 IP at AAA.  The Cards #6 prospect may not have as good of number as Gast, but he has a higher upside.  Like Gast, he could get the call if a starter is injured.

Oscar Tavares

Taveras is hitting .303/.351/.462 at AAA Memphis.  The Cards top prospect impressed during the spring, so much so that many thought he might break camp with the big club.  However, with the emergence of Matt Adams, the need for Taveras is not so great.


Kolten Wong

Considered the Cardinals second baseman of the future, Wong is hitting .292/.314/.408 for Memphis.  The Cardinals #5 prospect should get a look at some point this season, but for now it appears that the Cards are content with their offensive/defensive platoon of Matt Carpenter and Daniel Descalso.

Prediction

Overall, its rare that a starting rotation for a team remains intact for the whole year.  Usually a pitcher will suffer some kind of injury, whether it be a hamstring strain, oblique strain or even just a blister.  Thus, if I were a betting man, I would think the one of either John Gast or Michael Wacha will be the first to get the call and if I had to pick one of the two, I think Wacha would be the first to get the call.