Cards likely to keep Barton

The SLPD is reporting that the St. Louis Cardinals are likely to put Brian Barton on their opening day roster. This would make Barton the fifth outfield. The question will be if he can stay on the roster for the length of the whole season. In other words, can Barton stay moderately productive given limited playing time and not get caught in a numbers crunch? Thanks to MLB Trade Rumors for calling ttfc's attention to this.