I asked that same question a while back, and people said that the man-to-man defense is strictly defensive zone and isn't needed for AV's breakout system.
I don't agree.
These are my observations.
The Rangers, notably tonight, have stopped zone entries a lot more with the new man system. The full collapse Torts had them do allowed for very passive zone entries, making our own end look like a shooting gallery at points. This team takes away the lines when they can, and they negate zone entry, or force opponents to make a dump in.
A great example of how effective this can be for creating speed would be Nash's goal against New Jersey. Stralman stood up Greene at the blueline, Kreider and Nash went full speed ahead in the other direction, Staal stretched a pass to Stepan, and we've got a goal. The Devils barely blinked and we were on the scoreboard.
Also from the Devil's game, Zuccarello's second goal is a good example. Eric Gelinas left the line to step up on Pouliot, and Pouliot was far at the top of the blue line, where he was able to protect the puck and leave it for a streaking Brassard, which created a 3 on 1. In a typical collapse system, he'd be way below the blue line, and such a play wouldn't happen.
Man defense also has made our PK more effective, it forces other teams to make much quicker decisions. Albiet, if they CAN make those quicker decisions, the team can get burned. But it's been relatively successful, as long as the players keep tabs on their assignments.
There's a lot more examples of how the man system has helped, but I think you get it.