Here is a basic pressure with the defense sending the Sam OLB and rushing the 3 down linemen to create a 4 man line concept from a 3 down line personnel. The defense has several options about how to execute this call.
Two Gap DL:
One option for the defense is to have the 3 DL play a 2 gap technique. The LB makes a Right/Left call to tell the DL where the extra rusher is going. Here is a Left call.
Against the run the DL plays a 2 gap technique.
Against the pass the DL will work to pass rush lanes based on the Right/Left call. In this example the rushing LB is coming from the left. The left DE will work an inside pass rush lane vs. the pass. The DE has a 2 way go vs. the guard. The Nose will work to the inside rush lane opposite the call. The Right DE will work to contain. You can see this style of pressure in the 2008 Nick Saban Alabama Playbook.
Slanting the DL:
Some teams choose not to play a 2 gap defensive line technique and instead slant the DL to a 1 gap technique.
Here vs. the run the DE slants to the B gap, the Nose slants to the away A gap, and the away DE slants to the C gap.
Against the pass the slant technique plays exactly like the 2 gap technique.
You can see this slant style of 1 gap technique in the playbook of Wade Phillips.
Reduce to a 4 man Line:
The defense can also elect to reduce the rush to where they will be going and align in a 4 man line look.
Against the run the front plays exactly like it did when the DL slanted. The difference is the DL is aligned where they are going and play directly into their gaps.
The pass rush lanes remain the same.
This concept is also in the defensive playbook of Wade Phillips.
Stemming to a reduced front:
The defense can also choose to stem the DL from the base alignment to a reduced (Sink) alignment pre-snap.
Stemming forces the offense to react to the new alignments during the cadence.
All of these concepts can be accomplished while blitzing the Jack OLB as well.
A defense can elect to have any or all of these concepts is their playbook. Having more than one option can help the defense deal with some problem areas.
Slanting can be very effective. However, there are times when slanting the DL can be a challenge.
Against a gap scheme run play like power slanting can create issues. The DL in this example is slanting where the OL is down blocking. The DL may be athletic and powerful enough to avoid being washed by the down blocks. However the DL may get washed creating big seams for the RB to run through.
Another challenge when slanting is being able to deal with an OL that reduces their splits. In this example the OL is running outside zone with 6 inch splits. The issue is there is little to no space for the DL to slant to. Again an athletic and powerful DL can redirect off the zoning OL and make plays. However sometimes the DL is reached badly due to the tight splits and the defense has gap control issues.
In both of these situations being able to mix in 2 gap, sink, and stem concepts allows the defense to keep making a base call without slanting. Having all the options available can help the defense have a multiple plan and make in game adjustments based on what the offense wants to run.
Another reason to consider having multiple ways to execute a basic rush is due to variations in defensive personnel. On non-scholarship rosters the defense may have a wide variance in skill and talents among the DL. The majority of the DL may be athletic slanter types. But if you have 300 lb Nose who can't slant you are going to find a way to get that kid on the field. One solution might be to mix and match techniques.
Here the DE's are athletic players who can slant. The Nose is big and not a slanter. On the call the Nose stems pre-snap and plays the A gap without slanting. If the backup nose is an athletic slanter he can slant like normal but the big Nose will stem. Having versatility in a call's technique allows the defense to put players in position to succeed and allows the defense to play the most talented players.
Another choice the defense has to make is how the blitzer will play a TE. Again looking at Wade Phillips defense the rushing OLB can play inside or outside the TE using an Indian or Outlaw concept.
On the indian technique the rushing OLB (Sam) plays inside the TE into the C gap. The ILB (Mike) plays over the top of the Sam to the gap on flow to the TE.
On the Outlaw technique the rushing OLB (Sam) plays the D gap and the ILB (Mike) plays the C gap on flow to the TE.
While the concept of rushing an OLB in the 3-4 is simple there are multiple choices the defense can make to help make a basic call more versatile.