Michigan was passing a lot more in this year than we've seen from traditional Harbaugh outfits, and even by that standard this game was pretty extremely tilted to throwing the ball. Sometimes that's the gameplan, and it makes sense to be with a Heisman-candidate at quarterback.

Except I don't think that's the story here. Michigan's offense would love to run the ball, and their opponents would love to take that away from them. Again, Purdue was an extreme. So before we all panic about the running game I thought I'd use a moment to go over how the "No Name" defense works, what Purdue was doing to shut down Michigan's running game, and how Michigan still found ways to get around it without exposing McCarthy to runs. Like so:

How does Purdue's defense work? Why did this work so well against them? Why didn't Michigan's normal power runs work as well? Let's pull out our sharpies.

[After THE JUMP: Pinching edges punished precipitously]

THE 5-2 NO NAME

I went over this defense in more detail with Demorest last week, but that was video content so I'm guessing a lot of you skipped it. The short version is it's extreme man to man. Even more extreme than Don Brown. You have five large linemen? They have five large defensive linemen. You have a tight end? They have a strong safety. Receivers get cornerbacks. The quarterback gets a free safety. You have a running back? They have a linebacker for him, and goes wherever he goes. Put a fullback/move tight end on the field? Linebacker for him too.

Because they have a lineman for every one of yours, you can't run Michigan's favorite play—Duo—against them. That play is all about doubling the DTs and forcing a passive linebacker to choose his doom. If you start doubling the interior of Purdue's defense, you're just leaving a lineman unblocked; if you double two defenders now there are two guys unblocked.

Things may change up, with stunts swapping linemen, blitzes putting blitzers on backfield types, etc. Typically if they catch a Donovan Edwards shifting to wideout they'll have the LB swap jobs with a safety—the one time Michigan got that matchup was when Purdue was late to align after a change. They'll also use some switching to prevent offenses from getting too good at exploiting these matchups.

Here's the thing at work last year when Ryan Walters was the DC of Illinois.

Everyone starts with a guy. Note there are two very heavy-looking ends flared outside of their respective tackles. It's better to start outside and pinch inwards, because these guys are all about not getting edged and then pushing those edges closed. The interior DL are allowed to be aggressive, because if they get to the wrong side of an OL, there's an extra guy in the box to account for the RB.

On the snap they have to react to one of Michigan's linemen swapping places (Zinter pulls) while the rest of the line is blocking down. Easy enough. The edge on the left knows to look for a puller when line blocks away from him.

The SS also sees Honigford doing the same, and hops outside to be the new edge man so the DE can pinch.

As blockers declare their intentions someone gets to claim him and whoever was on him before gets to take the next threat.

This particular play worked because Michigan put so many guys on the line that they ended up with Corum matched with a DB who overran the play when Corum pressed outside.

This example was about as complicated as Harbaugh can make it, so hopefully you were able to follow along. The rules are pretty simple: you get a guy, and if your guy runs away from you, pick up the one coming towards you. Simple rules allow defenders to play aggressively, which is what coaches call playing football, IE trying to out-athlete, out-quick, out-think, and overpower another athlete. Illinois was able to play like this all afternoon last year, Michigan only managed to really punish it when Corum was still healthy enough to make plays, and Ryan Walters used the resume bump to get the Purdue job.

Of course using up an extra defender to have a man for everyone in the backfield save the quarterback has a few distinct disadvantages:

1. Your cornerbacks are pretty much running around in man coverage without help until the free safety.
2. The safety is very far away if the quarterback adds himself to the running game.
3. Chasing guys across the formation can lead to getting dusted by a sudden change of direction.
4. Pinching the ends can lead to getting edged.

APPLICATION TO 2023

In 2022 the first was mitigated by Having Devon Witherspoon, and the second was irrelevant because Michigan refused to subject McCarthy to QB keeps a week before The Game. They did so again when facing Walter's Boilermakers on Saturday, but Walter no longer Had Devon Witherspoon, and Michigan's passing attack carved up the secondary as much as McCarthy's accuracy and his receivers' hands could manage.

Most of that passing game was Playing Football, and thus not particularly interesting. But there were some tweaks that Purdue was using in the run game to deal with their weaknesses as well.

Here Michigan tried to go with a covered formation to create more space on the backside for Corum to make a play, but Purdue's pinching and using their linebackers to mirror the RB meant there was always going to be one unblocked guy you had to beat at the line of scrimmage.

I drew it up so you can see how the rules play out. The playside Edge sees his man block down so he looks up the puller coming across and gets inside of him. The WLB is getting outside to track the runner, who becomes the running back, and sets a new edge, constricting the space inside the edge and Barnhart's kickout. The MLB sees his tackle pull, lets the WLB know he's on the back, and tracks Corum to the gap.

Another note: if McCarthy had kept the ball he'd have to deal with the backside Edge—Barner can only provide a hinge—but if he can outrun that guy a keep is blocked to the safety. Who barely makes the screen at the resolution I draw these.

Because the free safety can't get there in any kind of time to deal with the quarterback, this becomes a problem for the guys on the front lines to deal with.

One way to deal with that is to bring the free safety down. Against certain looks (or when they thought they had Michigan's signs, apparently), Purdue would have that guy return from Argentina to replace somebody else. This is how Walter's defense likes to keep you off-balance. In this instance the safety is replacing the cornerback on top, who gets to blitz right into another Power GT run.

This means the backside edge is free to sit on JJ's read and force a give, where there's one more defender than Michigan has blockers for.

Again, there's still plenty of room here for Michigan to win the play. Henderson saw the cornerback too late but could have buried him in a way that cuts off the MLB. Last year we were seeing Corum do things like getting that MLB to commit to this gap then popping outside and running by the cornerback getting dumped by Henderson. You're still playing mano a mano, and there are opportunities to win big by breaking a tackle or getting a two-for-one block. But the tradeoff for Purdue is you HAVE to make a play to get anything valuable. If you execute yours and they execute theirs, because they're still playing up a guy in the run game, they have the advantage.

Of course if it's a pass and the safety is replacing the CB, that puts the safety in a two-way go with the receiver without any help. Which is why, I stress again, Purdue was getting their ass beat through the air.

So Purdue would rather take care of the quarterback problem by crashing the edges inside whenever they're unblocked, understanding that the reactions of the guys behind them will create a natural replacement on the edge. We're watching the guy on the top.

YMMV whether Henderson should be able to get out of a run set and pop that guy outside, but I think that's a very tough ask because the guy is going upfield and then in. The DE on the top and the LB behind him are running a crash/replace, which means the extra defender in the box is being committed to the quarterback and this needs to work because Corum's man is now the free safety all the way beyond midfield.

Now watch the other Edge, at the bottom, as he cuts off space, identifies Keegan pulling across, and jumps high of him. Keegan falls down and Corum is caught between a 280-pound rock and a 260-pound hard place. That gives the crashing DE time to catch up.

Michigan's play here is supposed to be messing with the No Name's rules. Bredeson's pre-snap motion draws a safety across the formation and that guy is a step behind, which gives Barner an angle to block him. The linebacker who had Barner swapped, which is another layer of difficulty and could be a mismatch if Purdue wasn't already putting a safety on Michigan's fullback in anticipation of some swapping. Walters wins this round.

A little later Purdue would abandon worrying about QB keeps but kept having that DE pinch high. Try to watch only the DE on the top and how Zinter dealt with him.

The threat of McCarthy still put the backside linebacker in a bit of a bind, and when Zinter was able to get enough of the crashing end on the frontside, Corum was able to scoot into the hole and play a little football against the unblocked WLB who had both RB and QB.

So what do you do about this behavior?

TRYING ZONE

When edges pinch you want to get outside quickly. The ones pinching from the backside should get outrun by the back, or give up a cutback lane depending on your run play. The one on the frontside has to be handled by kicking him out or zoning him off. Perhaps because the kicks were struggling to connect, Michigan brought out Stretch Zone at first. If you recall your Stretch rules, jumping upfield is considered Bad. That can create huge gaps to run into as zone defenders adjust and push you past the play. Watch #4, the Edge on the bottom the first time Michigan tried stretch zone with Mullings as the lead blocker:

As that guy gets escorted upfield past the hash mark, the run looks very promising.

Unfortunately Michigan isn't very good at running Stretch. Both Mullings and Barnhart take the same blocker and Edwards isn't patient enough to let them create a lane, so the safety can make it down, and the MLB to flow, and all that great playcalling karma is wasted on bad football playing.

Michigan tried this again without any more luck.

Here they motion to an I-formation, then take care of one defender by having Roman Wilson go in jet motion opposite the direction of the play. If you recall what Minnesota was doing to Michigan's front on Stretch a few weeks ago, this is the same principle. However Purdue's defense is on the opposite extreme from Michigan's. With two RBs in the backfield they've upgraded to a 6-1 front. It would seem Michigan won a block from that, because the safety on the fullback is starting from way in the back. From Purdue's perspective though, that's a license for this speedy player to crash and track the ball down from behind, putting a hard time limit on the run play.

With that Tackle (#0) going to set his high edge, that time limit is further compressed, but a good outside zone team would know how to take advantage of the space created by him getting so deep in the backfield.

Michigan is not a good zone team, however. Henderson is unable to delay his DT, Corum tries to go around the high edge and loses all of that ground, and the SS arrives from behind to hew it down.

This could have worked, but getting these blocks right in the moment takes hundreds of reps. Michigan hasn't put in the time to be a great Stretch team and doesn't have the agile linemen who make Stretch work so well. Purdue's defense plays against Stretch teams all the time, and their reactions are honed. The DT who beats Henderson and the safety who doesn't wait to chase it down from behind and the DT who set the high edge are all used to defending this weakness in their setup, and win their little individual football battles thusly. Michigan needed another way to attack it.

(Other than passing, which they were doing lots of, or having the QB draw a backside defender by reading him, which they didn't want to do).

FINE, LET'S MAKE IT A RACE

All along here I've been saying there are opportunities to make plays against Purdue's system: you just have to win a big individual matchup, preferably the one between the free tackler and the ballcarrier. The defense makes that hard by constantly switching roles as you move across the formation so they can deliver that guy to his spot cleanly. But there are ways to hinder his progress without inducing a switch, or at least to hide the need for a switch until late, or perhaps attack a guy who isn't very good at it.

Michigan found just that with end-arounds.

Now keep in mind, and end-around isn't really that fancy. It's mostly the same blocking, but replacing a receiver for the running back. It takes a lot longer to get the ball in your receiver's hands, however, so you need to make up the defense's increased reaction time with greater subterfuge.

The first of these was very close to a touchdown.

Here we have some pre-snap yo-yo motion from the fullback, with LB #42 getting caught a little further inside than he meant to by the quick turnaround. We also have that playside edge pinching inside, AND a cornerback in "man" on Morris who slams down on the running back. In the limited space of the above examples, these pinchers would be replaced immediately with defenders following their backfield assignments across the formation. But LB #42 is almost on the top hash when his man Bredeson is already moving his weight away from it, and with nobody to switch with him, the cornerback has to get through all of this traffic to keep up with Johnson.

Michigan's hoping to get them all overreacting to Corum so Keegan and/or Nugent can slip out and cut off the defensive backs. As it turns out Nugent gets held up on the edge that Tyler Morris is blocking down and Keegan might get to the cornerback in man on CJ.

Fortunately, however, the free safety hasn't picked up on where the ball is, and is coming down the wrong hash in case Corum pops out from the mess or something. If everyone makes their blocks they got this. Keegan juuuust can't get there.

The touchdown is still on the table though because Johnson is FAST and that cornerback has a lot of traffic to get through. After all the subterfuge, once again it comes down to the footballing.

Bredeson pops his safety another yard outside of the hash mark to make more room for CJ to run through, and Johnson uses that to nearly get into the endzone.

Purdue didn't change up anything they were doing, and Michigan mostly went to the passing game because that was working. But most of a game later they went back to this, and it worked even better thanks to the speed of Semaj Morgan.

Let's take what we know and go through how this worked out. Cornerback #13 is going to stay with Morgan across the formation, signaling to the free safety not to come down.

On the snap it looks like that outside zone they were running to no effect earlier. Seeing Henderson going away from him, the Edge, #5, crashes. Seeing Corum angling to (our) top, WLB #14 is going to move with him. On the top of the formation, the other Edge is also going to pinch inside and set a high wall, with the MLB hopping outside to replace him by tracking Bredeson.

With the FS playing in the parking lot to protect those cornerbacks from the speed of Johnson and Morgan, he's not going to be of any help here. Purdue's plan of getting a man to the point of attack has a critical problem: that cornerback cannot win a race to the point of attack with Morgan, and because of all the whip routes and stuff earlier he wasn't in a particular hurry to do so. Look how far behind his is at the handoff.

They *DO* still have an edge player in the cornerback on Johnson. However that cornerback will only activate as a run defender once he no longer has to guard Johnson in man. With his eyes fixated on the guy he might have to cover without help (if the FS helps on Morgan), the cornerback at the bottom of the screen doesn't know it's a run yet, and can't react until Morgan commits to crossing the line of scrimmage because Johnson remains a pass threat.

At this point the CB should notice that Johnson is going inside of him, that Morgan has the ball with no intention to pass it, and switch with his late-coming true freshman buddy. But CB#1 is no Devon Witherspoon. In fact he's the opposite; to PFF he went into this game as the worst run defender in the Big Ten.

I'm guessing that hasn't changed.

And one other thing: As true freshmen go, Semaj Morgan is a bit better than the free safety who's Purdue's leading tackler.

Yay for being better at football.

Thus ended the ~2 quarters of this game when Michigan's offense was struggling to move the ball and a couple of turnovers gave the Boilermakers some field goal attempts. It's a little disappointing that the more established offensive players weren't able to turn in highlight reel plays, but when not running stretch, they're still highly capable of running. Like anybody, they get gummed up by defenses built to commit an extra defender to the run every down. But with JJ McCarthy under center, even on a bad day for him, you probably can't get away with that for long.