This might explain what I mean a little bit better:
Gaps and Techniques
In the last few years, it has become common to refer to some defensive linemen as “3-technique tackles.” The term is usually thrown around without too much explanation, often by someone who might not know what he is talking about.
The “technique” being referred to actually specifies a location on the field and the responsibility that goes with that particular location. If a defensive lineman shifts a few feet to the left or right in relation to the offensive line, his duties (and the skills needed to perform them well) change accordingly.
The various field locations are numbered. These numbers are more-or-less universal: everyone from your local high school coach up to Tony Dungy uses the same numbers:
0-Technique: The defender lines up face-to-face with the center.
1-Technique: The defender lines up on the center’s outside shoulder.
2-Technique: The defender lines up on the guard’s inside shoulder.
3-Technique: The defender lines up on the guard’s outside shoulder, between the guard and the tackle.
4-Technique: The defender lines up on the tackle’s inside shoulder, though often coaches want 4-technique linemen face-to-face with an offensive tackle.
5-Technique: The defender lines up on the tackle’s outside shoulder.
6-Technique: The defender lines up on the tight end’s inside shoulder or (if there is no tight end) about 1.5 yards wide of the tackle.
The numbers break down a little at this point; different coaches will refer to the 7, 8, and 9 techniques in different ways, usually denoting linemen playing anywhere from the tight end’s outside shoulder to a yard or two wide of the offensive line. The higher numbers also change depending on whether the player in question is a tackle or end.
Stick a zero on the end of any of these numbers, and they can be used to refer to the locations of linebackers. So a linebacker in 50-technique is off the line of scrimmage, positioned between a tackle and a tight end on the tackle’s outside shoulder.
A 3-technique tackle, therefore, is one who usually lines up between the guard and tackle, with all privileges, rights, and responsibilities associated with the position. Each technique comes with a set of reads and keys, specific to the defensive system, the offensive formation, and the down-and-distance situation. In most systems, on most plays, a tackle lined up in 3-technique is supposed to shoot the gap immediately; in a 4-technique, one step to the right or left, his job might be to bottle up the offensive tackle so a linebacker can shoot the gap. In the 2-gap, tackles are often told to “draw responsibility” from two blockers, the football equivalent of “eating space” in basketball.
http://www.footballoutsiders.com/print/2704/
In the Jets' base 4-3 last year, the slant nose tackle lined up on the center's left shoulder, making him a 1 techique. He was supposed to hold ground and keep both gaps on either side of the center clogged, while at the same time trying to keep the LG engaged. This is why the SNT is considered to be a two gap assignment in Herm Edwards' Jets defensive scheme, although, as the article says, this can change based on the defensive play call.
The idea behind any two gap scheme is that the defense WANTS a given player to get double teamed.... eating up two blockers. He has to hold ground, and once he reads the play, either attmept to tackle the ball carrier, or pass rush, while staying in his lane. When a slant nose tackle does this effectively, the MLB is unblocked, and the scheme is designed for him to make the tackle.... again, most of the time. Teams may bring Safeties up, drop the MLB back, etc in a given play call.
Typically 1 gap schemes, like a traditional 3T, are supposed to shoot their gap, penetrate regardless of the offensive play call, and get into the backfield and disrupt the play.
Outstanding explanation.
