I found this piece that supports my belief that Jorge Posada should be the DH while Francisco Cervelli gets the starts at catcher, except this brings up different arguments.
I contend that Posada is a far inferior defensive catcher than Cervelli. Cervelli has the advantage in arm strength and quickness & mobility out of his crouch. I also said that Cervelli is just as good of a game-caller as Posada is, which is a testament to his maturity and promise as a 23-year old rookie.
This article says that the Yankees pitchers do better when tossing to Cervelli.
Check it out.