4-3 Under Base Defense

Let’s slow down today to look at FirstDown PlayBook’s 4-3 Under Base defense. Sometimes as football coaches we spit words out like “over” and “under” assuming that everyone understands us. That is not always the case. Sometimes coaches call things differently and yes, sometimes it just takes a while for a young coach to learn. No foul in that. We all did this at one time or another.

When FirstDown PlayBook refers to an under defense, we are talking about a defense that has these characteristics. First, the nose guard is shaded on the center to the strength. Here at FirstDown PlayBook, we always declare the strength to the tight end side or run strength. Strength could be called to the passing strength, the field or boundary or even away from a backfield formation.

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The end to the strong side plays a 5 technique, or shades the outside pad of the offensive tackle. If you have a tight end in the formation, the Sam linebacker will walk up and play a 9 technique on the that tight end. A 9 technique is outside shade on the tight end. On the weak side you have a 3 technique tackle (outside shade on the offensive guard) and a 5 technique end (outside shade on the offensive tackle).

There Are Variations To Your 4-3 Under Defense But There Are Also Staples

Your strong side linebacker or your middle linebacker will play the B gap. Your weak side linebacker will play the stack your defensive tackle and play the weak side A gap. Keep in mind that the linebackers will play their gap assignments based on run flow to or away from them. There are also other keys that go into this as well. We won’t get into all of that today.

FirstDown PlayBook Gives The “Have Nots” A Chance

Having said all of that, you will notice in the diagram to the right that there are several adjustments based on the offensive formation. That is important. You want to adjust based on a wing or a formation without a tight end. What is consistent is that the defensive line is in the A gap and C gap to the strong side and they are in the B gap and C gap to the weak side. The linebackers also keep their gap responsibilities the same.

FirstDown PlayBook Adjusts Your 4-3 Under Defenses & All Others To 27 Offensive Formations

This is where FirstDown PlayBook comes in handy. There is nothing flashy about getting lined up to formations when you are a defensive coordinator, but you can bet it’s critical that it gets done and gets done correctly. That is why we have taken on the tedious task to fit every FirstDown PlayBook defense up against 27 different formations. Of course you can then edit the drawing to fit your defense.

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We also include player assignments and coaching points for every defense. This is a big help when you have questions about making adjustments with your defense. We also do this for several other defenses including a 4-3 over, 3-4, and a 3-4 Bear. The variations like a 4-2-5 and 3-3 are also in FirstDown PlayBook. We will get to those later.

Take a look at this video that walks you through adjusting a 4-3 Under base defense to empty formations. It’s an older video but still helpful. When you take a free look at FirstDown PlayBook you will see that there are many improvements from what you se in this video.