Re: Matt Garza
If the Sox get Garza, I have to believe they'd be shipping him elsewhere. Imagine Crisp + Prospect for Garza and then Garza, Lester, Prospect (Lowrie?) for Haren.
Games are won on run differential -- scoring more than your opponent. Runs are runs, scored or prevented they all count the same. Worry about scoring more and allowing fewer, not which positions contribute to which side of the equation or how "consistent" you are at your current level of performance.