Do you have the advanced standings at the all star breaks?
It would be interesting to compare results in the second half with (a) results in the first half, (b) exp win % in the first half and (c) record in 2+ run games in the first half. When I did that one time (b) was the best correlate, which was surprising because I really expected it to be (c).
Which of these best predicts wins, or best predicts the others, is arguably the one that is best indicator of skill rather than luck. I still have a gut feeling that it's record in 2+ run games, but it would be good to back that up.