He told me that the biggest difference between the BYU/UU rivalry and the Ohio St/Mich rivalry was that in the former, some of the players actually hated each other and had no respect for the other team. In the latter, most guys respected each other and there wasn't really hatred. I think this all trickles down to the fan bases
PS: he also told me that they worked 2x as hard at Mich than BYU (Lavelle's BYU)