Establishing protection of the edge is critical in run support. The defensive ends and outside linebackers take on the less-than-desirable job of tying up offensive tackles and tight ends, keeping their shoulders pointed toward the line of scrimmage, and waiting for the running back to make a move.
When those players are able to do their jobs successfully, the inside linebackers and safeties can run to the ball carrier with little stopping them.
All of these things are much easier when players with the athleticism of Lawrence Timmons can reduce the amount of time the linemen and linebackers have to keep their position.
Timmons showed that at a level that may just land him AFC Defensive Player of the Week for his performance in the first half of the Steelers' 16-14 win over Philadelphia in Week 5.
Play 1
The Eagles have the ball 2nd-and-2 in the first quarter. It's been nearly as predictable as the sun rising in the east, teams are going to challenge the Steelers' front seven to take on stretch zone running.
That was a big concern in the Steelers' previous three games. It's not nearly as big a concern when James Harrison is on the field.
His quick first step against the stretching offensive line beat Eagles TE Brent Celek to the spot, and Harrison is strong enough to get a push on Celek, establishing leverage as they shuffle down the line.
DE Brett Keisel plows off Harrison's wake, disrupting the double team the Eagles' execution depended on.

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The fact Harrison and Keisel won their individual battles closed off McCoy's initial read, and with no back-side option, he squares his shoulders to the sideline (a cardinal sin if the back's goal is to gain yards) and tries to outrun the defense to the corner.
Hot in pursuit, Timmons knifes ahead of Harrison and beats McCoy to the corner, smacking him out of bounds, and setting up a 3rd-and-4 situation.
Play 2
It gets better for the new dynamic duo.
Harrison and Timmons team up for a well-executed scheme that resulted in Timmons' forced fumble.
The Eagles have the ball on a 2nd and 9 situation at the end of the first quarter. Vick is out of shotgun, staring at Keisel, who's assumed Timmons' inside linebacker position. Harrison is playing a 7-technique position with Timmons just to his outside.
At the snap, Harrison rushes hard outside left tackle Demetress Bell, and left guard Evan Mathis does a nice job of recognizing both Timmons and Harrison pushing out wide. Timmons stunts off Harrison, and it doesn't fool Mathis.
Vick doesn't have a receiver, and attempts to step up and escape.
The initial push didn't produce results, but it landed close enough to spook Vick out of the pocket. Watch Harrison as Timmons begins to spin off Mathis. Harrison and Timmons are essentially double-teamming Mathis, and if Vick had stayed put, they both may have gotten to him.
As it was, Timmons explodes to his left, and in about three steps and a dive, gets to Vick, hand square on the ball, knocking it loose.
It was recovered by Larry Foote (his second recovery of the game) after a yard or two gain.
Play 3
Those weren't the only two plays Timmons made in the first half.
On the Eagles' ensuing possession after Vick's (second) fumble, they looked to attack Harrison's edge in another zone run - this time, pulling Bell around Celek to block Harrison. C Steve Valos is supposed to chuck NT Steve McLendon, then get to Timmons on the second level.
Timmons read the play and was already well on his way to McCoy by the time Valos reached the second level. Harrison held his edge, forcing McCoy to either cut back in the face of Harrison and the pursuing Timmons, or try to out-run him.
It's pretty much a lose-lose situation for him, as Timmons closes the gap between him and the ball, and the guy carrying it. McCoy tries to get outside, and is taken down again by Timmons behind the line of scrimmage.
The explosion Timmons showed in this game, and Harrison's edge strength made it difficult for the Eagles to run all game. The helped hold McCoy to a season-low 53 yards rushing, and picked up a huge win.