The 4-3 is predicated on clogging the middle run lanes with defensive tackles and having defensive ends providing the pass rush. The Vikings have basically used that formula for their entire 52-year history. The 3-4 alignment has a huge nose tackle lined up over the center, with two bigger defensive ends to seal the edge and the pass rush being provided by the outside linebackers.
The genesis of the 3-4 goes back to college coaching god Bud Wilkinson at Oklahoma in the years following World War II. Suffice to say, it's been around for a while. The Miami Dolphins won the Super Bowl in the 1972 season using the first successful NFL variation of the 3-4 scheme. The Pittsburgh Steelers have used the 3-4 for almost 30 years, employing it initially more by force than by anything else. After Mean Joe Greene and L.C. Greenwood retired, there were rips in the Steel Curtain and Chuck Noll made the adjustment – a scheme that has remained for more than 30 years in Pittsburgh.
But it wasn't a defense that was overly popular in the ensuing years. In fact, as recently as 2001, the Steelers were the only team in the NFL to employ the 3-4 as a base defense. But, their success created copycats and that hasn't changed.
The cutting into the 4-3 pro-style defense didn't come overnight, but conversions were made. Initially, it was primarily an AFC replication. Baltimore has become known for its dominating 3-4 defense over the years and, until a recent switch, New England won its Super Bowl titles employing a 3-4 scheme.
The gap between the AFC and NFC is shrinking thanks to the success of the 3-4 defense. There are still more teams that use the 4-3, especially in the NFC, but the division is dropping.
Half of the 16 team AFC teams (the Jets, Ravens, Browns, Steelers, Texans, Colts, Chiefs and Chargers) use the 3-4. What makes that number ironic is that two teams that ran the 3-4 the longest (Buffalo and New England) aren't included on that list.
In the NFC, less than one-third of the teams (Washington, Green Bay, New Orleans, Arizona and San Francisco) use the 3-4 and the Saints have only recently converted to the new scheme. It isn't the norm in the NFC, but it's significant enough to make a dent in how teams are approaching the draft.
In all, 13 of the NFL's 32 teams (more than 40 percent) use a 3-4 alignment as their main scheme. That is good news for players that are viewed as classic 'tweeners – too small to be a 4-3 defensive end and too slow to be a 4-3 outside linebacker. With the proliferation of the 3-4, those prospects that were viewed as 'tweeners now are viewed as ideal candidates as a rush linebacker in a 3-4 alignment.
For the Vikings, this climate shift in the NFL has been viewed as a positive. Defensively, teams employing 3-4 defenses are looking for a different type of athlete – both on the defensive line and at linebacker – than teams that run a base 4-3. As a result, teams like the Vikings don't have the same level of competition for mid- to late-round defensive linemen and linebackers as those who run a 3-4 system.
It may not mean much to casual football fans, but the pool of talent that the Vikings are looking at in the draft – as least as it pertains to the front seven – is markedly different than what almost half of the rest of the league is looking for on draft weekend. Seeing as the Vikings are looking for depth at a minimum in the draft at both the D-line and the linebacker corps, the proliferation of the 3-4 may result in a lack of competition and some Day 3 bargains from the Vikings perspective.
John Holler has been writing about the Vikings for more than a decade for Viking Update. Follow Viking Update on Twitter and discuss this topic on our message boards. To become a subscriber to the Viking Update web site or magazine, click here.