From Joe Sheehan’s worth-the-subscription blog:
Bumgarner appears to be the odd man out for the Giants, who may be setting up a playoff rotation of Tim Lincecum, Barry Zito, Matt Cain and Jonathan Sanchez. This is a pretty good example of letting contract status and service time get in the way of the baseball. Bumgarner has been better than Zito from the moment he stepped on the roster, and the comparison between Zito and Sanchez isn't even fair. If the Giants slide Zito ahead of anyone, they're hurting their chance to advance.