A couple of days ago, I was trying to explain the defensive scheme the Broncos play to my girlfriend, only to get a vacant stare back at me.
At this time, I remembered reading a few blogs on many different sites, including this one, where a lot of the fans of their respective teams ran into the same issue.
I took it upon myself to do a serious amount of research and try to point out the differences among the countless schemes being employed in today's game but found it a bigger task than I anticipated, so I have boiled it down to 4 different schemes in total, within the two main formations, the 3-4 and the 4-3.
Not all 3-4 are the same, in fact there are various schemes ran out of this formation, because at the end of the day, the name 3-4 or 34 as some people like to call it, depicts a formation not the scheme.
This system employs three down lineman and four linebackers as their front seven. The three down lineman are each responsible for two gaps, with the nose tackle (NT for short) being the most important of all, followed closely by the two ends.
The NT will be responsible for the gaps between the center and each guard while the DEs are responsible for the gaps between the guards and tackles as well as "sealing" the end.
I believe that this the hardest scheme to find players for because the breed of athlete it employs is just hard to find.
This version of the 3-4 relies on the down lineman to "hold" the point of attack, other wise known as the line of scrimmage, making sure to tackle anyone coming down their respective gaps all the while taking on blockers to allow the linbackers (LB) a free path to the ball.
This requires strong, big, and heavy linemen that can move laterally with quickness, but it does not require penetration, that's left mostly to the LBs, especially the outside LBs.
In turn, this will require instinctive LBs on the inside and strong LBs on the outside to produce the pass rush. This scheme relies heavily on the OLBs to produce pressure on the QB.
This style of defense is great against the run but a little vulnerable against the pass. Another problem with this scheme is depth, as it relies heavily on the NT, which is a rare find in the NFL.
If your NT just happens to get injured the defense will suffer greatly due to the fact that NT are at a premium and very difficult to find, making the building of depth a problem. If you want an example see the Chargers.
Now a different scheme from the same formation would be the one-gap or "attacking" 3-4. This scheme was made popular by the Baltimore Ravens after the 2001 season, however, one of the first teams to use it successfully were the 1975 Broncos (although their best season with the scheme came in 1977).
While the same formation is used, the difference lies within the personnel. In this case the linemen are usually a little lighter and quicker, this is due to the fact that they will be given one gap to defend and will be frequently asked to penetrate and get to the QB.
This also requires a different type of LB, one that will be able fight off blockers and get to the ball. This style of defense does require one LB to be fast and instinctive and that's usually called the "jack" LB.
With this scheme, pressure is put on the QB from all angles making it excel against the pass, but it is vulnerable to the run. Some of the teams that use this scheme are the Jets, Broncos and Ravens.
The most important position with in this scheme are the LBs, both the ILBs and the OLBs. Speed and quickness are at a premium among the LBs within this scheme and that's due to the bevy of things they will be asked to do, anything from blitzing to man to man coverage.
While the two-gap system is designed to to funnel the ball toward the linemen, the one gap is designed to funnel the ball towards the LBs.
Now in the 4-3 there are four linemen and three LBs representing the front seven. This formation is a little less varied than the 3-4.
In most schemes, the four down linemen breakdown as follows, 2 DEs 1 NT and a DT(defensive tackle). Now I know I said one NT and the truth is, while many think the 4-3 employs two defensive tackles, it actually employs one three-technique DT and a five-technique DT, better known as a nose tackle.
This formation is all about the linemen, and therefore they are the true play makers of this formation.
Take, for instance, the 2002 Tampa Bay Bucs. That team might have been the truest incarnation of what a 4-3 defense should be, with two true pass rushers in the edges as DEs in Rice and Spires, one good NT in McFarland, and perhaps one of the best three-technique DTs in league history with Sapp.
The LBs also change in this formation. Let's start with the weak-side LB or "Will;" he must be fast and athletic.
The strong side LB or "Sam" must be big and strong, with the middle LB, or "Mike," being instinctive and a combination of both, but the linemen are the stars of the show.
The linemen's jobs break down as follows, the DEs will be responsible for the edges and applying pressure on the QB while the NT will be responsible for the gaps between the guard/center and tackle/guard.
Which brings us to the star of the show the DT, in the 3 technique, the DT is the one lineman that has free reign, he can choose his gap and "shoot" it, applying pressure to the QB and collapsing the pocket from the inside.
This defense is probably the most well rounded of all as it is strong both aginst the run and pass, but that is not to say that it is easy. Finding a true 3 technique DT, aside from the fact that they are more abundant, is probably just as hard as findinga good NT to play the two gap 3-4.
Don't believe me? Just ask Mike Shanahan or the 2009 Raiders.
Now I have left my favorite for last, and that is the "zone blitz" scheme. This scheme was perfected by Dick LeBeau of the Pittsburgh Steelers, actually he might have invented it I'm not sure, but he sure damn perfected it.
While the Steelers use a 3-4 formation, this is a scheme that could be used out of any formation, as long as Mr. LeBeau is teaching it, but for now we'll go with the two-gap 3-4.
This scheme is all about deceiving the offense, at any given time anyone on the field regardless of position could drop into a zone coverage or blitz, and yes, that includes the linemen.
That makes it almost impossible for the offensive line to adjust their protection scheme in order to account for a blitzer, which in turn causes confusion that usually results in pressure, sacks, or turnovers.
What makes this scheme go is the personnel, and you must have the absolutely correct personnel in order to run this defense and it takes quite a while to learn, that is why you will rarely see a rookie or young player start for the Steelers defense.
The linemen must be fast, strong, and athletic, along with all the linebackers and safeties.
Corners don't have to have blazing speed, since they will be responsible for zones and not man-to-man coverage. Along with all those attributes I mentioned above, perhaps the two most important ones are discipline and trust.
Each player must trust his teammates to be disciplined enough to do their jobs and not free lance, well Polomalu is the only one allowed to free lance, but he is usually right.
When this defense is at its peak it is virtually inpenetrable and perhaps the best defense against both the run and pass, although rarely using man-to-man coverage does have its draw backs, mainly against the pass, this scheme might just be the best of them all or at least its my favorite.
Well, that's all I have for today, and I hope I helped clarify some of the differences between defenses that sometimes can seem like they are all alike. Please feel free to comment and discuss.
Thanks for reading.