What are some good non-poll metrics for measuring the state of the race?

[geek tragedy]

In particular, ones showing that Clinton's ground game is plugged into the electorate and moving votes.

I think it has to be early voting statistics, in states like Iowa, Florida, Ohio, and North Carolina.

Clinton's team showed themselves very adept at using absentee ballots in the primary against Sanders.

We should see the fruits of that weeks before the actual election day.