Not sure if this is a true shift but at least I feel it is a topic that needs to be discussed.
Over the last decade we've seen a shift from the 3-4 run-stuffing defenses (our own version in the SB years, Pittsburgh etc.) that were physical (and aided by more "friendly" officiating towards defensive players) but not nearly as fast as the 4-3 cover 2 Tampa defenses that turned out to be the latest thing a few years back.
I personally felt we stayed with the same strategy of acquiring big but not necessarily very athletic players in the front 7 and that combined with our defensive backfield woes led to pedestrian performances from our defense.
The last few years we've seen the greatest defenses be composed of more freakishness (Seattle, San Francisco, Houston).
I feel the last two drafts of BB and company are interesting here. It seems like they are more inclined to invest early in very athletic players (Chandler Jones and Jamie Collins come to mind) that are fast, strong and rather big but thought to be somewhat raw coming out of school. Even Armond Armstead might be in that category (if he ever gets on the field).
Is this something to monitor? Are we slowly shifting in defensive strategy? Will we see more of that this year? Who will be targets if so (Kyle Van Noy is one player that comes to mind)?