Theory #4: Interference.

Not the kind from nincompoop Snyder and his cronies, but the kind the head coach or GM could introduce by mandating an approach. And one of the things M3 and Dom agreed they could not have were big plays in the passing game against the Defense. Dom was free to experiment but he couldn't allow quick scores via the pass. McCarthy pushed the nickel starting in 2010 and even more in 2011. He is a big believer in matchups and personnel groups.

Dom had featured leaky defenses that played better as the year went on until this year (in 2016 in went from good to train wreck to kinda pathetic due to injuries). I take that as a sign that the coach and the players need a long lead time to settle in for whatever reason (unstated above is the chance the assistant coaches were not working well together).

This year it started OK then got worse quickly. When they started hemorrhaging big plays, Dom sent Dix 25 yards deep and apparently threatened to harm his family if he got closer to the sticks. That was to stop big plays. But it so limited the coverage that they simply leaked everywhere with no pass rush. So you had a LOT of long scoring drives.

McCarthy approach to numbers is simplistic. He sees teams that win tend to run late so he runs a lot late with ANY kind of lead or game play. I'd bet a mortgage payment he has a similar approach to defenses that allow big plays/TDs being harmful to your overall record.

But if they learn Dom's D (or any D) during the season for whatever reason, then pulling the normal D in favor of the do no harm D in the middle of the schedule is bound to backfire.