ED, ask around. Big difference in recruiting at the D-III level and recruiting at D-I. D-III is phone calls and letters/post cards as D-III doesn't have the budget to recruit as D-Is do. The AAU trail and campus ( organized) visits make up a lot of D-I activity, entertaining and wowing the athletes. D-III sends them off to hang around the players lives. LOts of $$$$$$$$$$$ and attention at D-Is. Night & day. Interests and interaction with parents also key. Needless to say, if it was easy, many a successful D-III coach would be promoted to D-I. Rarely happens. And for good reasons.
I don't doubt that the way it's done is different. I'm just not ready to say the guy automatically can't do it. Buffalo may well regret the decision. We'll see.
I think, in general, too much is made of the supposed gap between coaching levels. I know a guy who was a D-III assistant, then a coordinator at the same level. Then a position coach in what is now FBS. I look up a few years later and he's an NFL coordinator, and a couple years later, a head coach in the league.
If you can coach, you can coach. If you can recruit, you can recruit. If you can do both, you'll be successful.