I wouldn't start Dessens againt St. Louis. The Cards have one of the top offenses in the NL with Pujols, Edmonds, Renteria and Rolen, although the game is at Busch, which is a fairly neutral park.
Daal might have a better chance, since both Cleveland and Tampa are weaker teams, but then again Baltimore is as bad or worse.
Frankly, these are both bad starts and both Dessens and Daal are weak pitchers that I wouldn't want to mess with. Do you not have anyone stronger on your staff that you can start?