But in this space, I'd like to talk about the 46 nickel as a possible answer to the smashmouth spread in general.
The Hokies' successes
Ohio State fans will be quick to note that their OL was young and JT Barrett was playing only his second game ever as a Buckeye QB when this happened, but it remains the case that Virginia Tech choked out their offense in that game.
Barrett was 9-29 passing with 219 yards at 7.6 yards per pass, one TD, and three interceptions.
The 7.6 yards per pass number is good and was the result of the fact that the 46 is a very aggressive defense of the "break don't bend" variety. The Buckeyes landed a deep shot or two as well as a slant route that went 53 yards for a touchdown. However, the overall inconsistency of the passing game in the face of loaded boxes made it very difficult for them to maintain drives.
The Buckeyes ran the ball 40 times for 108 yards with Barrett accounting for 24 carries and 70 yards while Ezekiel Elliot got the ball only eight times and produced 32 yards. The Hokies strategy was able to take the ball out of Elliot's hands and force the Buckeyes to try and flank them on the perimeter. Urban Meyer struggled to do so.
So how does this work?
The 46 Nickel
The 46 defense was made famous by Buddy Ryan's 80's Chicago Bears teams that won the 1985 Super Bowl. The idea was to cover every single opposing offensive linemen with a defensive player to make winning the line of scrimmage difficult for the run game, to apply pressure to the offense, and to allow the middle linebacker and strong safety #46 Doug Plank to run to the football free from advancing OL.
Rex and Rob Ryan have modernized and used the defense since in the NFL, most famously in Baltimore with Ed Reed sitting on the back end to clean up anything that survived the pressure cooker they created up front.
Here's what a 46 nickel defense can look like against the smashmouth spread's favorite formation, the spread-I.
On the edges you have a Sam and Will DE/OLB player like in a 3-4 defense, except that they rarely get dropped back into coverage in this defense but instead get to focus on controlling the edge and forcing the ball between them.
This has the nice effect of freeing up the corners and nickels from any primary responsibility for run defense so they can focus on playing (usually) press-man coverage on the wide receivers.
Inside you have two tackle/strongside end players in three-technique positions who are attacking the guards and making it impossible for them to get to the second level. You also have a nose guard attacking the center who's often a two-gap player.
This is where the 46 could really do damage today as teams often use smaller (6'2" 290 is about average) quick thinking players at center who can make line calls and survive the brutality of the trenches by being involved in double teams with the guards. It's very difficult to double team any of the DTs in the 46, so that center is almost always on his own.
The middle linebacker might have to take on a lead block now and then, but he and the strong safety (or rover in V-Tech's terminology) are mostly going to be running free to the football. The ball is going to be funneled right to them more often than not but it's essential that they reliably be in position to make the tackle when that happens.
As Bud Foster himself has noted, the boundary corner and free safety probably have the toughest jobs in this defense. The free safety needs to prevent back-breaking plays and be in position to clean up anything and everything that breaks through the wall. Virginia Tech often moves him around to either play up tight to the line of scrimmage to be an 8th man in the box to stop the run, as a robber in the middle of the field to sit on intermediate routes, or as a very deep centerfielder.
The boundary corner is working in isolation against what is often a top receiver without deep safety help and he can't play too loose unless he's really consistent on breaking up slants.
I'd add that the nickel has a tough job too since he and the free safety often have an eye on the run game and he's working in a lot of space against the slot receiver.
Stuffing the smashmouth spread
The smashmouth spread is largely built around attacking the middle of the field with inside zone and gap schemes like power. The offense is trying to space players out so that they struggle to get their hats to the A-gap with leverage to avoid getting blasted by the OL, FB/TEs, and the ball carriers. Hence the "smashmouth" element of the system.
The 46 nickel's "bear front' makes it very difficult for any of these schemes to work effectively. Let's start with the zone read play with a lead blocker for the QB:
The edge contain player, "W" in this diagram, stays wide so the QB hands off to the running back. The defense only has a double team in the cutback lane inside of that "W" so that's where the RB needs to go. However, the defense knows this and the mike can easily scrape back into that lane with the strong safety and free safety following closely behind him. There's very little chance of the tackle coming off that double team of the 3-tech and reaching the mike backer in time.
The defense forces the offense to work within narrow spaces with the wide contain players and then it becomes very hard for the offense to win those battles because so many DL are working against single team blocks while the middle linebacker and safeties are flowing to the football without having to worry about running into OL.
Let's look at power now.
Meanwhile, the offense still has no major advantage at the point of attack. The double team is going to really struggle to release an OL to the strong safety or middle linebacker before they clog everything up and if the strongside contain player (S) is good at squeezing the block by the fullback (H) than the ball is bounced outside and your "smashmouth" scheme is now featuring a RB running parallel to the line of scrimmage.
Normally the smashmouth spread punishes the defense for sending numbers to the point of attack aggressively with run/pass conflicts created by RPOs, but there are no easy RPO answers to this defense because the secondary, other than the free safety, don't have primary assignments against the run. The only players that could be attacked in conflict are the middle linebacker and strong safety and since they are keying the back and the tight end/fullback respectively, they're going to know what's up pretty fast.
Problems for the 46?
The "all or nothing" approach of the 46 makes it possible to do real damage in the run game IF the offense can find ways to get enough leverage to make that happen. This can be accomplished primarily by getting more receivers in action so that the front is reduced.
That can be done in a few ways, one is just to motion a player out of the backfield so that the defense only has one support player left in the box to fill gaps with.
"dread wing" offense can always find ways to overstress a defense. However, even now a spectacular player at the nose tackle position who just beats up the center can wreck this play. The defense could also drop the free safety down closer to the box to get their numbers advantage back.
It all comes down to how well that nickel and those corners are doing at holding up in coverage outside, and that's where you can really attack the 46 defense, with the passing game.
There's not much point in using the two-back run game against the 46 since you'll never get angles or advantages at the point of attack like with normal defensive fronts, so the first response to the 46 should be to space it out with four receiver sets.
A slant route that gets open can mean six points in a hurry against this defense and it's not terribly hard to get the weaker coverage players ($ and M) in some tough spots:
The limited options left to the defense from playing aggressively at the line of scrimmage makes you wonder if this defense can work against the more pass-savvy smashmouth spread teams and whether it's a non-starter against an Air Raid squad of the sort you often find in the Big 12.
Will we ever see the 46 in the Big 12?
Despite the Air Raid being the more dominant strain of spread offense in the Big 12 over the smashmouth spread, for now at least, the 46 may have a future in this league and actually already does find some use.
Many defenses actually do regularly utilize the 46 defense, but without lining up in the basic structure. Instead, they get there via the man-1/fire zone. Many fire zones serve to create the same kind of 5-2 or 5-1 defensive front that features wide contain players, 1-on-1 match-ups for interior DL (or blitzers), man coverage outside, and a deep safety sitting on top.
3-4 teams in particular have very little trouble creating 46 fronts with the blitz. The difference is that they can try to scheme their blitzes to avoid leverage disadvantages or to try and create extra penetration by disguising who's playing which positions.
Every Big 12 team's favorite anti-spread defense, cover 4 with man coverage outside, bracket coverage on the inside slot receiver, and the backside safety playing in the box could quickly rotate into the 46 after the snap with a blitz:
What would be truly fascinating would be if a team made the 46 alignment a big part of their base defense and supplemented it with coverage calls designed to shore up soft spots:
As more and more coaches find that the only way to consistently beat good, modern spread teams is to be capable of outscoring them, more teams will adopt aggressive defensive strategies that can either get them the ball back quickly or yield a quick score that still picks up the pace of the game and gives them a chance to wear out the opposing defense.
Whether teams utilize the 46 as a base package, something they show now and then, or something they get to via the blitz don't be surprised to see this classic scheme find some utility in the modern game.