I wish I could find it, but I did a somewhat related analysis a few years back along the lines of "what percentage of Nebraska's total program wins have come against Iowa State, Kansas, or Kansas State?". Of course, historically, those 3 are among the absolute worst D1 programs of all time (not hyperbole, their all time W/L records support this assertion) and, historically, Nebraska played all 3 every year for decades on end.
Nebraska's win percentage against those 3 was astronomical, which I expected. What I *didn't* quite anticipate was the total percentage of wins those three programs accounted for in Nebraska's all time record which, as I recall, for the window for which I did the analysis, was something near 1/3rd of Nebraska's all time total wins.
Obviously, Nebraska has had some incredibly impressive program achievements but they also benefitted greatly from being spotted 3 near auto-wins for many, many years on end (and, remember, for much of that time, teams were only playing 9 or 10 game schedules, so being given essentially a free 3-0 is nothing to sneeze at). I don't think it can be ignored.
The Big 8 was a very weird place in terms of having 5/8ths of the conference being made up of statistically (all time W/L) very extreme teams (Nebraska, Oklahoma, Kansas, Kansas State, and Iowa State). I don't believe any other long-standing conference demonstrated such polarization for such a prolonged time period.
