40 doesn't seem to be the magic number from what I am seeing in Argento and Bava.
Here are the teams by world in D1AA along with win totals, D2 wins and NCs.
HardKnox23 37 wins, 31 D2 wins
KatzPhang88 37 wins, 29 D2 wins
Scoobybud 42 wins, 27 D2 wins
dewagne (me) 52 wins, 34 D2 wins, 2 NCs
EZ37 39 wins, 29 D2 wins
WVUFan76 32 wins, 25 D2 wins
RunRun 39 wins, 29 D2 wins
AppSt 38 wins, 30 D2 wins, 1 NC
dewagne (me) 52 wins, 36 D2 wins, 1 NC
Looks like D2 wins may be a factor, but not sure but when a 32 win coach gets to move up, it sure looks like it.