Stubbs can start vs. LHP not named Jaime Garcia. No prob. (.839 OPS vs. LHP)
Stubbs can start vs. the Astros and other AA pitchers. No prob.
Its the rest of the games which are up for debate. And that includes the playoffs where he will be facing elite pitchers.
Of course, you can always reduce the impact of his terrible bat vs. RHP by dropping him down in the order. From 2nd to 7th he gets almost a full 1 PA per game less. But I think I've heard that idea a few times before around here.