All those old polls are from before the primary, i.e. before Republicans coalesced behind Dunleavy. I'd need to see new polling before concluding Begich is anything but a slight underdog here.
About 1,200 people have already returned absentee ballots. Some of those are presumably wasted votes for Walker.
I've never understood why early voting needs to start this far before election day.
Even if we pretend that March polls tell us as much about the outcome of a November election as October polls, two of the polls he cited were basically Democratic internals. My guess is Dunleavy wins by 3-5, although I wouldn’t really be surprised by Dunleavy +8-10 or Begich +1-2 either.