The Steelers had some difficulty stopping the outside stretch play from the Kansas City Chiefs on Monday night. As is often the case in football, the fault does not lie with one particular issue and/or player. Instead, the relative success of the Chiefs' running game can be attributed to a few factors.
The scheme of the Kansas City Chiefs was a big factor. They used one primary formation to run the ball: slot receivers (Bowe and Baldwin) to one side with a TE flanking the other side of the formation. This formation forced the Steelers to roll their coverage to the slot. As a result, a safety was taken out of his normal run fit, which would be A gap weak (away from the TE).
The Steelers normally start out of a 2 high shell and rotate their safeties accordingly. One can stay high while the other can come low and fit in run support. This is why the Steelers play both Troy Polamalu and Ryan Clark as both free and strong safeties. It helps greatly with disguise in both the pass and run games.
Whichever safety rolls down is usually responsible for cutback. Pre-snap, it's weak A, but that changes as the ball moves wider on the line of scrimmage. The safety's fit allows the backside linebacker to flow fast to the play; he does not have to worry about the cutback. Against the Chiefs, the Steelers chose not to do this because of the offensive alignment.
It seems as if the Steelers were content to let the Chiefs prod at them with the run, but were determined not to give up a big play. The Steelers did not give up any big plays to the Chiefs' wide receivers, but the linebackers struggled all night with the cutback.
As was stated above, the technique of the Steeler linebackers (particularly Larry Foote) was below the line as it came to run defense. They seemed to be pursuing much too perpendicular to the line of scrimmage. This flat angle allowed Charles to cut back underneath them.
The Chiefs have the ball first and 10 on the Steelers' 12 yard line with 8:42 remaining in the first quarter.
They had been running effectively, but two big pass plays on bootlegs set them up in the red zone.
At the snap, Foote read the play as a stretch run to the defensive left side (something they'd done multiple times on this drive. Instead of pushing the gaps, though, Foote plays it very flat, taking a straight angle from his starting position, mirroring Charles, the ball carrier.
The play was called for LB Lawrence Timmons and DE Ziggy Hood to stunt, with Hood crash over the A gap and Timmons taking on the guard.
NT Casey Hampton jumped to the backside A gap (defensive right side), likely by design, but without Foote filling that space, there's a huge seam between Hood and Hampton. Logic suggests that's where Foote should be, playing the cutback while LaMarr Woodley, Timmons and Hood tie up blockers at the line of scrimmage.
But because Foote approached so flat, center Ryan Lilja reached him at an angle well away from the play, leaving safety Will Allen alone to make a play. He can't, and Charles goes in for the touchdown
For Casey Hampton to have even laid a hand on Charles is impressive, considering he started by going one gap to his right, then coming back two gaps to his left.
Hampton was not responsible for the B gap.
Not that the defensive line was without fault, though. bigger technique issue, however, resided with the defensive line. It has been repeatedly stated that the Steelers play defensive lineman that 2 gap. This means that the defensive lineman has a primary gap (normally outside of them) while also maintaining the ability to fall back inside if the play cuts back.
In order to accomplish this, a defensive lineman must have terrific upper body explosion. A defensive lineman must be able to use his hands to stun the offensive lineman and force separation. This separation allows the defensive lineman to do exactly what was just mentioned: maintain his primary gap while also having the ability to react inside. Power, coordination, and hand placement are all vital to achieving separation. The Steelers, for some time on Monday night, could not just do it.
Chiefs have the ball third and three from the Steelers' 27 yard line, 10:14 left in the third quarter
The Steelers call a fire blitz with Timmons and Foote, with the intention of getting Foote into the B gap. They read the play perfectly, but the execution from DE Ziggy Hood and Woodley isn't powerful enough to stuff the play.
Foote had a chance to knife in the gap and at least force Peyton Hillis to take an away angle to escape - Hillis is already running with his shoulders toward to the sideline, which is essentially like a shark smelling blood in the water for a defensive player. Foote fails adjust his route to the ball carrier considering he was moving more horiztontally than vertically when he received the handoff. Foote gets too close to the tackle, who's chipping off Hood, and releasing.
Clark is run-blitzing, and comes down to the ideal spot for him to read and shoot through the gap to make the play. Both he and Foote get caught in the wash but do enough to get a generally slower running back like Hillis to turn hard to the outside. He shouldn't be fast enough to get to the corner.
However, Hood fails to gain outside leverage on the tackle, so the tackle can release to stop Foote's pursuit. If Hood was strong enough in this play, he could have forced Hillis to run even further toward the line before cutting up field.
The biggest part of this play, though, is Woodley's lack of explosion. This is a tight end blocking him, not a tackle. He has the edge, but stands up a bit too high, and cannot violently throw off the block and make the play. He gets an unbalanced tackle attempt at Hillis, who runs through it and gets the corner. He turns it for a first down.