NFL defensive schemes

I guess it shouldn't be a surprise that as a Patriot fan that I favor a couple packages I have seen the Pats run over the years. I personally believe that the 34 defense is the stronger base defense compared to a 43, and I heavily favor the 1-5-5 sub nickel package as well in passing downs.

Let's first examine what the 34 defense is built for. You base your team around an "anchor" defensive (nose) tackle to take on multiple blockers and cover multiple gaps. In many cases they do the dirty work to help free up opportunities at the next level of the defense. They are more built for pure strength then for more of a speed rush ability. This also is a characteristic that the defensive ends are created for. They have a bit more flexibility not having to be pure run stuffers, but they also use gap control. They need to dictate changing the runners lane to inside or outside depending on what the defensive call is. You usually don't see how sack totals for any of the lineman. Your linebackers feed off of what the line creates. Your outside linebackers are in control of sealing off a runner to break outside, and kick the play back in. In passing downs they in many cases bring pressure,  but can be used in zone coverage. The inside linebackers rack up a lot of tackles if the nose tackle does his job. Their responsibility is shutting down interior movement. In passing down they can be left in zone of man coverage on a tight end of running back.

I feel there is a greater advantage when running the 34 defense compared to a 43 defense. You have more speed on the field, having an extra linebacker over a lineman. This allows you to have more zone defense, and can run the risk of man coverage with safety help deep. In many cases, even against the run you're outside linebacker has good enough size to engage and contain run plays. It also creates more unique blitz packages allowing you to overload a side, or cross your middle linebackers with a delayed blitz.

A under the radar formation I like is a sub nickel package, the 1-5-5. Used is longer passing downs, it is thrown in a couple times a game. You're only using one defensive lineman, with five linebackers. When you use this, the linebackers usually are constantly moving before the snap creating confusion on who is blitzing and who drops out in coverage. This leads the quarterback into calling a play without a full knowledge of what the defense will do. Once again you have better speed on the field, with a single lineman and many linebackers. It gives flexibility in what kind of blitz and coverage schemes you run.

Even though I favor these techniques, it truly comes down to what personal each team has. You can't run a system most players aren't familiar with or moving a player to a position they aren't known for. In many cases a outside linebacker is looked at a defensive end or vise versa depending on their size. Strategy and game planning have a major factor in determining what you run from week to week. Having the ability to practice and use multiple defenses at all stages of a game increases the success rate of the team.