I understand and do not disagree with Bochy's decision to start MadBum in game 2. I appreciate his faith in the young lefty. However, the decision seems to have interesting implications with regard to Matt Cain and games 6 and 7.
Inserting Bumgarner between Zito and Vogelsong (RV) makes perfect sense in that it avoids starting RV on short rest. In fact, it adds a 5th day of rest for both RV and Cain, assuming they start games 3 and 4 in Detroit, respectively. Probably they are a bit tired and this will be a good thing. It sets up Zito for a perfect 4 day rest starting game 5. Additionally, it sets up RV, arguably our best pitcher right now, for game 7.
However, starting Cain in game 4, instead of 3, means he can only start one game this series. [An alternative would have been to start RV in game 2 (on 3 days rest) and then Cain for game 3 (on normal rest due to the travel day).] Thus Cain's role has been diminished by this choice.
Personally, I like the choice to start MadBum and thus diminish Cain's role. Cain may be tired. Vogelsong has been a rock, but perhaps it would be unwise to tempt fate by having him pitch on short rest against a team that is strong against right-handed pitchers?
One last note: game 6 becomes a question mark with our current path. If Bumgarner does well tonight, then the question mark is erased. The rotation becomes: Zito, Bumgarner, Vogelsong, Cain. On the other hand, if Bumgarner struggles tonight, who pitches game 6?
Of course if the Giants win in 5, all this becomes moot. We'll see. Go Giants!