Rock, paper, scissors is a great analogy.
Defenses are being built to stop those passing teams. Underhill has already pointed it out but the big interior linebackers like Brandon Spikes don't really exist anymore. Massive amounts of money are being spent on pass rushing DE's and CB's. Teams spend more time in nickel so their nickelback's have gotten a whole lot better while their 3rd and 4th linebackers have gotten worse. Mobile QB's have introduced another dimension they have to consider.
Right now all these teams are heavily invested in passing and stopping it. It'll take a while for them to re-tool if they even want to. We kind of have a blank slate developing over the next few years and our new coach is the ideal candidate to get ahead of the curve.