I think you're making a lot out of one particular weak spot in his ratings. The problem with any rating system that claims to rate both FCS and FBS schools on the same scale is that there aren't enough games between them. Including G5 and P5 on the same scale is hard enough when each team plays at most 1-4 games with the other group. Not all FCS schools even play one FBS school, and most don't play more than 1. That's just not enough data to include both on the same scale.
Sagarin's college football ratings are referenced by many national media outlets and common fans as the "gold standard". I argue that he is exceeding the capabilities of his model by ranking FBS and FCS teams.
You point out flaws that need no further explanation. There's no prize for doing too much (ranking FBS and FCS teams in the same system). Without an FBS only Sagarin rating we are left with only his overreaching model to judge. And I argue that it's modeled at the expense of the G5.
FCS teams ranked unrealistically high are merely an indicator that other P5 teams are also ranked unrealistically high in the Sagarin model, further compromising the realistic rank of G5 teams (like the MAC).
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I think Sagarin's Top 10 is realistic, maybe the Top 20. And to me the realism of Sagarin Ratings declines significantly thereafter the further the teams get from the top. This is what I mean by exceeding the capabilities of his model.
To draw a comparison to another popular math model (that was once but is no longer the "gold standard"), Newtonian Mechanics, I'll steal some language from the internet: (I'm not comparing Newton to Sagarin or Einstein to me. I'm making this comparison to say, "Hey, here's something that's popular. Something that the common man is aware of. Here's it's limitations. And here's a better way to go beyond the currently popular math model's limitations.)
"In Physics a "theory" is a mathematical model based on various assumptions and valid for a limited range of physical conditions. Newton's laws are a mathematical model that is limited to non-relativistic speeds and low gravitational fields, and within those limits it is exceedingly accurate. There is no sense in which Newton was proved wrong by Einstein. What relativity did is expand the range of physical conditions over which the theory applied. Special relativity extended the range to include high speeds, and general relativity extended it again to include high gravitational fields. Even GR is not applicable everywhere because it fails at singularities like the centre of black holes. We expect that some future theory (string theory?) will extend GR to describe places that are singular in GR." -- John Rennie
"There weren't really any hints that Newtonian gravity was limited until special relativity came along and raised problems. In the context of pre-SR mechanics Newtonian gravity was a complete theory. It would have been natural, but not justified, to assume then that Newtonian gravity was exactly correct. This is the sense in which GR "overthrew" Newton." -- Michael Brown
http://physics.stackexchange.com/questions/52165/newtonia...