I absolutely agree that we need to move to man defense. However, although every zone defense has a hole in it, man defense has weaknesses as well. All it takes is one mismatch. One player that is faster than his defender, or can jump higher, or can gain separation, and it's serious trouble. Personally, I wouldn't mind seeing a man defense under safeties playing cover-2 or over-under with the outside CBs. Since we're still playing a three-man line, but now have linemen that can get to the QB, we now have the flexibility of dropping an extra person back into man coverage with the safeties over the top if they bring out three receivers. Even they bring out three, and send the RB and TE on a route, we're still sending four guys at the QB while covering and keeping the safety net over the top.