1) So is the 80/20 split discussed above you or your co-worker?
2) In your universe, does the offensive line always escape blame when "less than a fraction of a second after Franklin was handed the ball he was met in the backfield by more than one Bengal?"
3) You seem preoccupied by the conclusion that the Packers seemed unlikely to convert on that play, which is fine. I didn't like the play call either. But if the fumble hadn't occurred, the Packers still hold a three point lead and turn it over on downs at the Bengal 30-yard line. An unfortunate result but not disastrous.
4) The play became a disaster because Franklin failed to secure the football. I've watched the film and I'm astounded by your willingness to overlook this in order to advance the argument that MM's play call was the most egregious thing ever...
It's not complicated. It's high school football 101. The RB's primary job is to secure the football because, there's no guarantee he won't meet defenders in the backfield. That's not on McCarthy and that's not beyond the abilities of a rookie RB in the NFL.
5)
"What in the way of evidence can be derived from that the run up the gut had a good chance for success." -How about the fact that the Packers had a good afternoon on the ground against the Bengals up to that point. Discounting his 51-yard scamper, Franklin still averaged 4.3 yards per carry and had plenty of gains running between the tackles earlier that day. There's your evidence.
I get that you have an agenda with regards to foisting the lion's share of the blame on McCarthy for this play. I just hope others can consider all the facts objectively and recognize that there's plenty of blame to go around.