Yes I see your logic. However, that sort of logic applies to a conventional race with conventional candidates. The problem with Trump is he can't control his worst impulses. Was watching a 538 podcast the other day and Nate Silver made this very point: that an ordinary candidate can better take advantage of opportunities to come from behind than Trump can because Trump is sort of stuck in a self-destructive loop that he is unable to extricate himself from.
That's why I predict, among other things, that the second debate (which used to be the third debate) will be a reprise of Trump behaving the same way as he did in the first. In spite of negative feedback and declining poll numbers after the first. Because he can't help himself. He only knows one way to behave.