Quote Originally Posted by Harlan Huckleby View Post
Well, it is supposed to be "cumulative regular-season point differential since 1920"
I read that to be a running total of all game margins since 1920. Perhaps I misunderstand, but that's what it says.
That means the accumulated margin of victory (if you are willing to live with negative margin of victory for losses).

If you went with an average for each team, that would exacerbate the problems with different eras.

To both look at the historical record and consider eras, you would need a differential between a teams yearly margin of victory and total scoring or standard deviation.