This will continue until teams start moving safeties up and perhaps even utilizing what used to be the strong safety position more. After a while of that, the deep ball will open up again. To me it's the natural cycle of the game. As this current trend continues, I'm sure the league will implement some ridiculous rule to give receivers a bigger advantage instead of the letting this evolve organically. Nothing wrong with a RB busting a 12-15 yard run.