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.
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.
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.