It's an obvious connection: the more starters you bring back, the more the team will improve in the first month of play. SBN college football numbers guy Bill Connelly wasn't content with that obvious correlation: he wanted to know by how much, because he asks such pertinent questions. And he did the graphwork.
He was surprised that teams with several returning starters get better, then keep getting better (as opposing to leveling out). And, yes, teams with fewer returning starters begin the year worse then gradually improve.
It's relevant to us because there are three MAC teams total on the extreme ends of this spectrum: Toledo and Temple, both enjoying 9-4 years and bowl victories (but no division titles), each bring back nine starters. In this scenario all returns are created equally although we both know that TU and UT both bring back multiple quarterbacks with starting experience. Notably the Rockets lost Eric Page, who declared for the NFL draft but also senior running back Adonis Thomas and pretty much damn near the whole OL graduated. So they may start out about the equivalent of field goal worse than normal and, well, potentially stay that way. But Toledo doesn't kick many field goals in the first place, although this could potentially CRIPPLE the Owls' favorite way of scoring. Hang tough, Brandon McManus!
On the other extreme, Bowling Green improved from 2-10 to 5-7 with a young bunch, mostly on defense, and got better, mostly because of defense. BGSU returns a crowded 19 starters, tied for third most in FBS. So the law of averages says they'll be immediately better by about a field goal, which they'll need to at least cover whatever ungodly spread shall be laid against them in their opener to Florida.
And of course, "number of starters" could mean all sorts of things, but the important points are which starters are gone and how much experience they had. For example, even though BGSU isn't losing many starters, wide receiver Kamar Jorden was crucial the last two years and I think center Ben Bojicic has been sorely undervalued the last three years. Yes, they're getting many people back, including four of their five offensive linemen. But the center, captain is leaving. That's more than just "one starter leaving."
Maybe down the road somebody will have the time and the lack of social life to crunch further into which teams are losing the most experience. But especially for the MAC, it comes back to that damn talent gap between teams which is so ridiculously small. In the end it may come down to luck, location and opportunity. For example, Temple has a nice schedule next year. Reportedly they'll have OHIO, EMU, Akron and UMass at home, with road trips to Buffalo, Kent State, WMU and Miami. Might just work out for them! And then Toledo will reportedly draw Akron and Buffalo as their MAC East crossover games. That seems more on their side than "nine returning starters."