We often hear the term "setting the edge" but rarely are we told what it means. To be effective against the run, the defense must keep the running back from getting an unobstructed run into the alley. The alley is the area from the last man on the line of scrimmage to the sideline.
The defensive end, the Strong safety, the cornerback or the outside linebacker may be charged withe setting the edge. Kentucky was particularly vulnerable last season to runs into the boundary. The defender setting the edge must hold the point of attack and turn the runner back inside, or, create a stalemate with the blocker causing the runner to bounce to the outside. When a runner must bounce further outside, this allows the pursuing inside linebackers the time needed to kill the play at the sideline. This is referred to as "spill and kill" .
The two players who will primarily be setting the boundary edge this season will be Jabari Johnson and Jason Hatcher. Below is a clip of Jason Hatcher and another of Jabari Johnson where they hold the point of attack which allows the middle linebacker time to shoot the open window and make the play from the inside out. The edge defender and the inside linebacker must work together in order to stop the run into the alley. ( You will notice in one clip the linebacker misses the tackle despite having a free run at the ball carrier.)
When the edged defender gets a pass set he has to again maintain the edge and ensure the quarterback is not able to escape the pocket and extend the time line. Notice Jason Hatcher in the following clip sets the edge, then uses his hands to displace the blocker and is able to sack the quarterback from the outside in.
When a defense begins to give up significant yards it is typically a combination of elements. The most common breakdown comes when the edge defender either gets "kicked out" wide or gets pinned inside. This results in a larger gap for the inside linebacker to fill. The clip below shows Jabari Johnson getting pinned inside, and the fullback is able to block the inside linebacker as there is no edge defender to worry about. Because the edge was opened, the fullback was free to block the filling inside linebacker. ( The inside linebackers have to be better at shedding such blocks, but that is for another article)
And here is a clip showing the edge defender getting pushed out wider, allowing the running back a free run into the alley. The inside linebacker does not have time to fill and the play gains over 5 yards.
With the suspension of Jason Hatcher for the first two games, Jabari Johnson will need to use the extra strength he has gained this off season to set the edge allowing the linebackers the freedom to fill the gaps with an unobstructed run.