Differences between 4-3 and 3-4

[renojedi]

I understand the basics of what it different between 4-3 and 3-4 (i.e. number of DTs vs. LBs) but can someone explain all the nuances of the two defenses? What are the other major differences between the two?

I constantly read how it is a hard transition to make between the two, you have to have the right personnel, etc. but I am not sure what players are best in which systems or why adding another DT, for example, is such a "huge" transition for the teams to make.

Thanks!

[richierich]

Basics: Ideally in a good 3-4 defense you have to have a good DT who can draw a double team, and two defensive ends. Then any of your LBs can be the 4th guy on the dline, or however you want to rush the passer. Usually the 4th LB can both rush the passer on certain downs or cover if need be. It can disguise your defense a lot more than 4-3. But you have to have the right personnel.

[marktg30]

The post above puts it into the best layman's terms.

Basically, if you want to look at a team perfectly built to run a 3-4 Defense you will go with Pittsburgh.

They have three starters on the D-Line that are 285+. This will give them the ability to demand some attention up front which opens up the LOS (line of scrimmage) for athletic LBs.

Their heaviest starting LB is 265 lbs. Every other guy is between 230 and 245. This means they are going to be very fast and able to pull off crazy blitz packages. (Which is why Dick LeBeau may be one of the best DCs ever)

On the other hand, the Browns are a team still trying to transition to a 3-4 from a 4-3. They have a good start with Shaun Rogers in the middle. However, their LBs are not as athletic as the Steelers and their DLine other than Rogers doesn't command as much as attention on the ends as you would like to see.

As far as your secondary goes in a 3-4, it depends on the coach's preference. Pittsburgh has a bunch of enforcers in the secondary that will knock the snot out of you, even on the corners. Polamalu is a beast in general.

Cleveland has a couple ok coverage CBs and two average Safetys).

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The 4-3 currently at perfection is probably Minnesota.

Jared Allen, the Williams Duo and Ray Edwards make the D-Line the source of most teams' anquish. Most 4-3 schemes involve the pass rush coming from the athletic DEs. (Think Reggie White, Bruce Smith, Julius Peppers, etc.).

Then the Vikings have Chad Greenway and EJ Henderson as their 'standout' LBs.

The secondary, like the 3-4 is really based on preference. I am of the opinion that Minnesota has gone for hard hitting over coverage. Antoine Winfield is one of (if not THE) hardest hitting CBs in the NFL.

Hope that helps.

[lonewolf371]

There are two huge differences: the importance of the nose-tackle in the 3-4 and the fact that the defense's featured pass-rusher stands up in the 3-4.

In the 3-4, because the team only has 3 down linemen (less beef), you need those 3 linemen to be a lot bigger. Arguably the most important man in the 3-4, the NT (that's Vince Wilfork in New England, Casey Hampton in Pittsburgh, Kris Jenkins on the Jets, used to be Jamal Williams in San Diego, Jay Ratliff in Dallas) is supposed to control the middle of the line of scrimmage and allow the linebackers to make plays. They're often called "two-gap" linemen, because they're responsible for the gap on either side of the offensive lineman they're engaged with.

The second-most important player in the 3-4 is that team's featured pass rusher, who is essentially a defensive end that doesn't have his hand on the ground. The pass-rushing linebacker will actually blitz more than he drops into coverage. These guys usually have the highest sack totals in the league (Shawne Merriman in San Diego, DeMarcus Ware in Dallas, James Harrison in Pittsburgh, Vernon Gholston on the Jets). If you don't have a great NT and a great pass-rusher, the 3-4 will generally fail.

The two middle linebackers in the 3-4 are essentially exactly the same as the "Mike" or MLB in the 4-3. They almost always drop back in coverage and have some of the highest tackle totals.

The requirements in the secondary are also slightly different in the 3-4, but not much. Generally the corners don't have to be as athletic and they play zone most of the time.

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The 4-3 is a more traditional defense with four down linemen. Generally, the linemen are responsible for a single gap (a DT will immediately try to rush forward between a guard and tackle). The 4-3 also has a featured pass rusher, although in the 4-3 he also has to be big enough to stand up to an offensive tackle and stop the run. The advantage is that you have a lot more beef up front.

The linebackers in the 4-3 are generally smaller than those in the 3-4. In a lot of 4-3 defenses, the play is funneled towards a specific linebacker (often the ROLB or weak-side guy) that has high tackle totals. All three linebackers are expected to be very good in coverage, and don't blitz as much as 3-4 linebackers.

There is a higher requirement for athleticism in the secondary of a 4-3. The corners will often be required to play more man-coverage.

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Finally, the reason you see two defenses is that you have a large number of players that come out of college called "tweeners," or guys that aren't big enough to play defensive end but are too slow to play linebacker in the 4-3. The 3-4 was essentially created to give those "tweeners" a spot on the field, because a lot of times they're excellent football players. However, the number of required "tweeners" for all the 3-4 defenses in the league is about equal to the amount of "tweeners" that are coming out of college right now, so there's a relative balance now between teams that are switching to the 3-4 and are switching away from it.