I actually think it's wrong to think of Sanchez as being responsible for the buttfumble. It was incredibly amusing, but it was really caused by Vince Wilfork assaulting Sanchez with one of his own linemen. Coulda happened to anyone!
The entire ST did spend a week working on that play except the snapper got sick on Saturday and Whalen replaced him and had less than one day to learn and rehearse the play, IIRC. Unfortunately he made history in the worst possible way, for something that was not his fault.
I'm with @maust, this is not at the Funt (which I have never heard until this thread), Jim Marshall or butt fumble level. I'd go so far that Desean Jackson dropping the ball at the goal line is ahead of this, as is the Pats lateral vs the Raiders. This isn't a play of stupidity, it's just a dumb bounce or bounces.