A stunt, also called a twist, is a move on the defensive line that involves two players exchanging responsibilities.
A 9-technique aligns outside of the tight end. They are typically pass rush specialists and aren’t expected to contribute as much in the run game.
-techniques align on the inside shoulder of the tight end. Another, more intuitive name for a 7-technique is a 6i.
6-techniques align directly over the tight end and opperate as edge rushers. They use speed to collapse the pocket and provide pressure.
5-techniques align on the outside shoulder of the offensive tackle. They have to be sturdy in run defense while still having pass rush ability.
4-techniques are usually 3-4 defensive ends. They’re a little slimmer than 3-techs and work almost exclusively against tackles by alignment.
A player on the outside shoulder of the guard is a 3-technique. 3-techniques are a little more slender than 1-techs or nose tackles.
A 1-tech is a larger player who can withstand a double team and ensure that the 3-tech gets a one-on-one matchup.
At its core, a 3-4 defense has three defensive linemen and four linebackers. It has versatility while keeping the same personnel on the field.
The 4-3 Over puts it’s 3-technique or B-gap player to the strength of the offense and keeps the Mike linebacker clean to make plays.