His dog won pretty handily in the last election, though. It's not an exact science, but his methodology seemed to eliminate a fair amount of doubt from the equation.
If there's a gradual shift in the polls, I'm not sure what that would mean. Which scenario did you have in mind?
I have a feeling that polling is used now a political weapon not a measure of reality.
Unlikely, considering there's one every other day
(that's actually not the best method to evaluate him, because he provides estimates of chances and could be better evaluated with something like the https://en.wikipedia.org/wiki/Brier_score that checks for calibration as well, but it's more intuitive).