It's called "the nickel formation". You may have heard of it.
Snarkiness aside, I would be good with going into a Big Nickel 4-2-5 as the base. Basically, the premise is that you are increasingly getting into a passing league, and you get matchup nightmares like Gronk and Jimmy Graham, or people running the ball out of shotgun spreads like Chan and Chip Kelly like to do.
The pass threat is so deadly that teams now predominantly play the nickel, but it opens up holes for the zone run game. The counter is the "big nickel", bringing in 3 safeties so one can drop into the box while leaving the other two in pure coverage.
If that's what McD is trying to do I am all for it.