NFL teams are absolutely obsessed with the defensive line. Finding players who can consistently provide pass rushing pressure is very hard to do, but teams use a lot of draft picks and spend millions on free agents in an attempt to do so. A team that can pressure the quarterback gets all sorts of attention form the public and the media. One that can stuff the run is a bit more under the radar, but no less valued by team management. The best way for a defensive front to provide apply pressure is a topic of much debate and contention, and there are about as many advocates of 3-4 schemes as those that back a 4-3.