There is a trend that has been building for a number of years on the defensive side of the ball, and that’s increasing speed. Virtually every position on the field has had to undergo an evolution over the course of the past couple of decades to become more athletic.
Instead of Casey Hampton at nose tackle, you now have Javon Hargrave as the archetype. Instead of James Farrior at linebacker, you have Ryan Shazier, and now Devin Bush. Granted, the secondary has always prioritized athleticism, but the general trend has been clear.