Even if the challengers' numbers aren't the best, Arnold's are just miserable for an incumbent. Not to mention if I remember correctly his approval ratings are lower than every governor in the country except Frank Murkowski and a certain character from Ohio. That he is going down is something I have very little doubt of.
There is an old logic problem that goes something like this: you are a recruiter for a baseball team. You have two players try out by running to first base. One makes it there with perfect form; the other with an ugly, sloppy gait. Which one do you choose? The one with terrible form. Teach him good form, and he'll be able to outrun the other.
Likewise, you choose the candidate that can be most improved, not the one that is currently doing best. With a nearly 2-to-1 disapproval, an incumbent being down only four points or so is extraordinarily good. Schwarzenegger can't really go anywhere but up at this point, so Angelides and Westley are clearly barely hanging on.
Undecideds often break against the incumbent, especially unpopular incumbents. Silly Republican apoligist.
