Not to turn this into a baseball discussion, because it isn't, but one thing that us hardcore baseball types argue about is the concept of 'timelining' when attempting to compare eras, evaluating quality of players, and teams.
It goes far beyond, 'DeadBall era' (pre 1920) vs 'Live ball'. Rule changes. League wars (AL/NL/Federal League), the WW II era, the most obvious pre-integration, post-integration, expansion era, park factors, PEDs, and greenies, etc.
I guess what I'm saying is, college football has many more variables than just three clean periods, pre-poll, post-War, and 'take your pick' (for the third option). I'm willing to acknowledge at a macro level, those are fair periods to identify, but there's more to it than meets the eye.