So this should never ever happen again:

You've been hearing all offseason that Don Brown will ask his cornerbacks to play more "trap" zone and be more involved in run fits, most recently in Adam's interview with Zordich:

MGoQuestion: How much more important, if at all, is run support from corners going to be this season compared to last season?

“Very important because of our trap system, the system that Don Brown brought in from Boston College. Our corners are going to be very much more involved in the run game.”

However they'll mostly be doing the same stuff they did last year. Brown indeed has a Cover 2 thing he'll bring out, but most plays his defenses are in a Cover 1 ("City") or Cover 3, just like D.J. Durkin's. How will that be different?

HOW DON BROWN DEFENDS THE PERIMETER IN GENERAL

Before getting into that specific coverage we ought to understand the terminology and general thinking behind Brown's run fits. So you know how there are gaps between offensive lineman, and that these gaps are named alphabetically starting from the center. So the A gaps are between the center and the guards, the B gaps are between guards and tackles, C gaps are between tackles and tight ends, if the latter exist. From there some coaches are content to keep adding letters all the way to the sideline.

That's not how Brown names them, on pg 63-64 of the 2013 Boston College playbook, where he shows the lane responsibilities for his two base coverages: Cover 2 and Cover 1 (or 3):

Those terms:

CREASE: Brown defines it as the "zone run area outside the tackle box and inside the #2 receiver." The second part is not totally accurate; eligible receivers are counted from outside-in, so often enough the #2 receiver is a tight end lined up tight to the line, in which case the crease is outside of him. The point is the crease is the first big lane outside the tackle box, where a lot of zone runs take place.

ALLEY: To Brown it's the "run lane inside the corner but outside the [outside linbackers'] support window. The safety must keep his inside pad on the ball for example." In other words this is an extra crease created when there's more than one wide receiver on that side of the formation. Since it's way out there where OLBs usually can't get to, the alley usually has to go to a safety. However it's not always the case, especially once he's got his coverage hybrids out there in place of the OLBs.

OUTSIDE: The run support lane outside the wide (#1) receivers. This is where cornerbacks take if the WR doesn't just go downfield, and bubble territory.

[After the jump: How Michigan did it, and will do it]

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PERIMETER CHOICES

Crease defense is one of the first strategic decisions a defense has to make: do you go with quicker defensive ends and have them defend the edge until safeties arrive, or trust quicker linebackers to handle it while you bulk up DEs who dive into gaps, or have your safeties and MLB stay down while everyone else squeezes the play back to them (MSU).

Spread-to-run offenses live and die by their ability to exploit the space in the crease, probing the defense's choices and altering their attacks based on that. A classic example was Durkin's strategy for defending Ohio State's spread last year. Durkin's plan was to play a "soft" edge with two excellent DEs (Wormley and Taco), meaning those guys are kind of two-gapping—dominating the guy across from them so that neither lane is open. That won't handle the whole crease, so the plan was to have the safeties clean up, bringing down the one on the short side.

The first play here is a pass, but the dump-off to the RB makes it functionally a run.

Last year Michigan's favorite changeup from its base Cover 1 was Cover 3, which is not all that different from Cover 1. Michigan didn't play it great—the H receiver came open on his in route when Ross and Bolden both converged on the flex tight end—but since Barrett looked away right before it, there's no harm. But I want you to see how Dymonte is playing this at the bottom of the screen:

Michigan was a gap defense, with 10 players each given a gap and a high safety back to clean up. Technically Henry is supposed to have the B gap (black line) but Peppers is back there to assist if Barrett breaks out, while Dymonte has his eyes and can maintain leverage to make sure Barrett goes where he's supposed to. The ball goes to the running back in the flat, and Dymonte makes a great play, keeping the ball on his inside shoulder to tackle an amazing athlete in space.

The second play Michigan went back to their base coverage.

Again, it's Dymonte isolated against Ohio State's superb running threats, and again he wins (WHY OH WHY WAS THIS GUY NOT REDSHIRTED AUGGGHH). Michigan started both safeties highish then walked down the one declared strong (because the TE stayed there) and had the other back out into high coverage. This was the plan all day: start with two safeties high, bring down Dymonte to support the edge on the strong side.

Dymonte also has the RB, who's helping the TE block Taco, if the back goes out in a pattern. The other safety, Wilson, went deep; he's out of the run fits entirely.

This time Barrett would run into that huge gap, and again Dymonte played it textbook, keeping his shoulders square—the ballcarrier on the inside shoulder for leverage—and making the tackle: 4th down, nothin-nothin, with Michigan set to end the first quarter with the ball in Ohio State territory.

The strategy on both plays is pretty basic: here's my guys, there's your guys, let's see if your guys can beat my guys. However on 4th down the punter rolled way out of the pocket and made contact with the guys trying to block it, the insano Big Ten refs forgot the rules of football, and Ohio State was awarded 15 yards and a 1st down.

At this point I want to mention that Brown does this same thing. He likes his DEs to be big burly guys who attack the edge blocker, gumming up the edges of the backfield to nerf sweeps and the like. But remember the Cov1/Cov3 diagram above?

The high safety isn't cut out. He's got a crease. In fact everybody's got a run fit here, and everybody's shifted over to match the run blocking.

Back to last November: Now Urban knows Michigan's plan of attack: every DL and LB has an interior gap, one safety is going to be way back and out of the run game, the cornerbacks are just going to be playing the outside receivers all day, and the other safety is hanging around where he can help man a frontside gap, but can't abandon the crease. Michigan is saying pick your poison, which worked most of the year because almost every player on Michigan's defense could kill you, and the weaknesses of the linebackers were mitigated because Glasgow could kill two people.

But Urban looked around, saw no Glasgow, and said "I'll take Ezekiel Elliott versus linebackers for sixty, Alex."

After a first down pass and a timeout Ohio State starts moving that tight end:

Frick you, Urban, frick you! gob mannit, flup you! FLUCK!

FWIW Brian calls this offensive play "Inverted Veer." It's the play that Borges used to run incorrectly (he blocked the playside DE rather than read him) and Denard/Gardner ran effectively anyway. Ohio State made it their base play last year and with Ezekiel Elliott flying through the Crease it was deadly.

Now Michigan should have adjusted to that motion TE better; the backside is over-manned with James Ross over there, and Ohio State's tendencies mean Bolden should be shuffling at least as far as the QB. Morgan tried to fire into that motion TE but got picked off by the crack block of the flex TE already to the strongside. Wormley got read and wound up too inside to force a keep, but used himself up against the pulling guard to mitigate that. Dymonte attacked the Alley, keeping leverage on the motion TE, but that's a TE versus a DB and Thomas has the worst possible angle to squeeze that crease smaller.

With the pulling guard taken out by Wormley though there should be a free hitter. Ross is coming all the way from the backside, so he's not going to make it. Bolden didn't react to the pulling guard immediately, but did shuck the OT and might run this down, and you're not expecting the weakside linebacker to shut this down. Morgan is D-E-D dead.

A big gain becomes a monster one when Jarrod Wilson, returning from the parking lot, takes a bad angle too far inside, turning 15 yards into most of them.

#NEVERAGAIN

Let's go back to just before the snap.

No way does Michigan defend this from here. You'd like Morgan to get outside his blocker, who is lined up 5 yards outside of him. But he's coached to shoot into the tight end he's over, which just makes him even easier to block for that other TE. The lesson here is Michigan's "Let's play 10 on 10" strategy just bit them because the offense turned it up to 11—spread offenses make you account for the quarterback.

And Don Brown isn't having it. Here's what he says right after those two edge defense graphics I showed:

ZONE READ COMMUNICATION:

READ – Communication between LB and A/E. This tells LB’er to play appropriate gap with DE reading the mesh with QB responsibility to help on the zones crease. DE always chases QB when he has kept the ball, from the inside out

BEND - Communication between LB and A/E. This tells the DE to bend on the zone with LB’er playing the QB right now. LB’er and DE must switch jobs if the OT bumps or fans the DE.

And here's what that looks like, via Steve Sharik in HTTV:

Brown will have the End and Mike play the read aggressively. The basic attack—Read—has the DE (Wormley) reading the mesh and calling out where he's going to make it go so the Mike can get in position. Sometimes the DE gets caught out with the RB, usually because he got bumped out there by the releasing OL, and yells "BEND!" so the LB can bend inside and take the quarterback.

Note how the defense hasn't left defenders way back there. It's not Dymonte Thomas out there with a tight end but the SAM: James Ross last year and Jabrill Peppers last year. And the MIKE is a crease defender, not trying to shoot into an inside gap off the snap. The Will is attacking with the pull rather than trying to follow along and dodge blockers. And most importantly that safety is coming down when the strength is declared with the shift.

This is probably how it was supposed to go with Durkin, but to keep Jarrod Wilson the high man they wound up with the wrong personnel—to play a 1-high (cov1 or cov3) defense from that would end up with James Ross playing high. That's a tactical error, but one brought about from the strategic error of playing Ohio State like they're BYU.

Brown's got another attack to shut this down which actually preserves that free safety, again courtesy of Sharik:

You wanna play option, we'll play option too. The SAM here is reading the motion tight end at the snap to decide if the play is going inside or out. The middle linebackers are attacking upfield super-fast, the Will crossing the Mike when he reads pull. The SAM sees the motion TE release outside and instead of waiting for him to control the Alley, the SAM blasts up into the crease. As for the alley: what alley? All I see is a mess in the backfield, with linebackers closing in.

(Course you have to make that tackle—BC ran this against Clemson last year and got burned for a long gain when the SAM dove inside the motion TE, the RB slipped the tackle attempt, and the alley was everything from the hash to the sideline).

And then of course there's that Cover 2 thing.

Imagine the #2 receiver on the left side is a tight end. He motions to the right side, and the front seven shift with him, with the FS backing off into what looks like a middle third zone. However this is Cov 2. The FS and R are backing into deep zones and the cornerback to that side, who's got the flat zone, sees run and is careening into the alley. True that's a bad matchup for him, but on the other hand the Rover is still in the area, and you're not expecting a cornerback in there.

Brown's got more stuff but these are three base things that can all shut down Ohio State's base thing with different techniques. Not having the luxury before of units where every guy can beat the man across from him, Brown's strategy is more to choose the offense's poison for them.