Your probability in the hiring process requires full context, yet such is missing and causes you to overlook good candidates including potentially Belichick. Time for a revision.
There is a trend, and the sample size is not small. Ditka, Jimmy Johnson, Gibbs, Lombardi, Parcells, Seifert, are some of the bigger names. No head coach has won a Superbowl in 2 different stints. I have evidence, you don't, so stop trying to refute it. Besides, despite that trend I'd still hire one of those coaches. My point, again, was that trend would have been a better argument than your surface-deep argument against hiring Shanahan.
Shanahan won with a roster mostly built by others? Really? That argument shows that you in fact are operating with negative bias and not using sound reasoning despite you calling for such in this thread. Talk about doing everything you can to take away credit. He didn't even win those Superbowls right? It was all Elway right? Drafting Terrell Davis didn't help out at all right? Elway had great success before Shanahan and anybody could have won with him as QB right? Unbelievable. You've lost me now. If your goal was to drive away those with different opinions by not presenting the same sound reasoning you asked for yourself, then congrats.
And simply stating "repetitive," as you just did to me and have done to others, when we are refuting points you repetitively are raising, is going against what you are asking others to do in this thread, is rather disingenuous, and is telling of the weakness in that specific argument.
I for one will be rooting for the team rather than watching with a foregone conclusion of failure. It is not a grounded opinion when you have already determined a conclusion multiple seasons in advance. You are not practicing what you preach when your reasoning leads you to conclude things far into the future which you can't actually know.