In the last five years, the 3-4 defense, which is characterized by its creativity and deceptiveness, has been extremely effective in keeping QB's off balance. However, it seems that more and more teams are switching to this base formation.
ProFootballTalk reports that the number of teams which operate out of the 3-4 has quintupled this decade, expanding from three teams to 15. In 2000, no NFC teams used the 3-4 as their base formation. Now, five do. The NFL has become a pass-heavy league, and teams are looking for ways to throw different looks at QB's to keep them off balance. The 3-4 does just that.
Formation-wise, the 3-4 is relatively simple, and is comprised of three defensive linemen, four linebackers, two safeties, and two corners. It continues to gain in popularity --- four of the top five overall defenses in 2008-09 employed a 3-4. Three of the top five sack leaders that year were from 3-4 teams.
OK, so what about the 4-3, is that formation obsolete?
Leslie Frazier, Vikings Defensive Coordinator, said he actually prefers the 4-3 because he thinks it's easier to find the interior defensive linemen who power a four-man line than All-Pro-type linebackers that the 3-4 needs (per PFT article). LeBeau thinks it's easier to find a "gifted" 245- to 265-pounder who can line up in a two-point stance on passing downs and confuse the offense as to whether he'll be rushing or dropping into coverage.
So what does this mean for NFL defensive schemes in the future?
While we don't know for sure, there is a good chance opposing QB's will be more prepared for the 3-4. If more and more teams work out of this base formation, offenses will continue to spend more time studying tape of it, and will find ways to sniff it out pre-snap and be able to counter it. Most of them are probably already doing so during this offseason.
So could we see a role reversal and witness the 4-3 as the most effective base formation once again? If teams continue to show too many looks out of the 3-4, that certainly may be the case.
In case you missed it, Niners Nation did an excellent breakdown of the 3-4 and what it entails earlier this year. Check it out (here)