The pendulum in the NFL is swinging back to the defense. Defenses are effectively capping explosive passing offenses. This is causing an evolution of offenses towards heavier personnel and the running game. In time, this is going to cause defenses to shift from speed and coverage to size and power. And the cycle will continue.
I just hope that the NFL doesn't start tweaking the rules again to even further skew towards passing and offense. Just let the game evolve. There will be ebbs and flows over time, and that is ok. It allows teams to be innovative.