It appears Western Michigan is subscribing to the Northwestern-Pat Fitzgerald model; get a successful alum who coaches, since the other candidates may bolt at the first whiff of success.
See:
Haynes, Paul
Taggart, Willie
And further back:
Schembechler, Bo
Along with numerous other examples of guys who played their supposed "alma mater dream jobs" into the next big $$ gig.
Not buying it. He has success, and he'll go chase the money/glory somewhere else. Sad reality of college sports.