Yeah, exactly this.
If you look at his most successful D, the No Fly Zone in Denver... he had very good press man coverage, solid, super smart Safety play (Champ Bailey), fast, young ILBs that can get sideline to sideline, pass rushing OLBs and one super great DL (Derek Wolfe)
We have never been closer to having the roster Wade needed to succeed than we are now.
The issue on D is that we've had guys selling out to get penetration, sometimes losing gap responsibility because teams have been easily completing the short passes and even when the run wasn't particularly effective (9ers averaged less than 3 yards per carry), they were still able to convert and sustain long drives... keeping our D on the field and preventing our O from getting into a rhythm.
What playing man does is make the QB take that extra second or go deeper into his progressions.
That brings the pass rush into play. When Denver would beat up on NE, it was because they were able to stifle Brady and make him wait just long enough for the pass rush to get there.
Wade's D just doesn't work running lots of zone.