One major criticism of spread offenses is that they struggle in the red zone. I think there's some truth to that - you need to be able to run the ball downhill especially when you're inside the 10-yard line. Spread offenses are meant to create space and attack voids, but as you approach the goal line, you lose space. There's no vertical threat when you're inside the 5, so defenses can concentrate on stopping the run and the short passes.
Feel free to chime in with a comment below about this either way, as the stats aren't really all that conclusive - there was a mix of "spread" and "pro-style" teams in the top of the red zone efficiency rankings, so make of that what you will (also keep in mind those stat factor in FGs as red zone "success" - count only TDs and the rankings look fairly different). I think that plenty of other things affect how well you do in the red zone, as no matter what you run it's hard to overcome missed blocks, penalties, turnovers, etc in the red zone.
Either way, when you're inside the red zone, you have to change up your offensive philosophy no matter what you do. Mazzone's short-yardage/goal line package is going to look familiar as he uses the pistol formation, specifically with 3 backs in what is generally called the "pistol diamond".
The pistol diamond is something that started becoming popular a few years back. I remember seeing Oklahoma and Oklahoma State messing with it, and Dana Holgorson over at WVU has really started integrating it into his offense (Tavon Austin just scored another TD on Clemson with that jet sweep out of the pistol diamond). I don't remember seeing us run anything with 3 backs in our little pistol experiment (maybe someone can correct me - I only got to watch half the games this season). I know we used a 2-back pistol formation inside the red zone a lot.
The advantage of the pistol, in Mazzone's case, is that he can still use his zone key game by motioning out one of the upbacks, just like how he does out of his 3 and 4 WR sets, but use alignment to run the ball more downhill. If the defense doesn't respond to motion, the QB can take the snap, pivot, and throw it immediately, instead of dropping back, planting a foot and throwing. Otherwise he can hand it off to the back on the inside zone.
The pistol diamond series is fairly cheap, meaning that it's similar enough to the rest of the offense that it won't take up a lot more practice time (keeping in mind it's a situational package). For the most part, Mazzone ran inside zone, zone key, and some kind of playaction out of his look, all things they do in their regular offense as well.
Zone blocking is the basis of the rest of Mazzone's running game, so this is nothing new - just a different way to line up. Out of the regular shotgun formations, Mazzone controls the backside defenders (prevents them from playing the run too hard) by reading them with the quick backside screen or the zone read. Out of the pistol, he just blocks them with an upback. Simple stuff. Note that there's an unblocked safety backside - this play only really works if he stays at home. If he cheats in to play the run, then you have to do to protections, like playaction or the zone key to force him to stay out there.
This is the same concept out of the base formations, just a different look. Linemen block the same and the QB makes the same reads. Main difference is the path of the back, he takes a more downhill path as he's directly behind the QB. Motion either removes a defender from the box to open up the inside run, or puts a speedy guy on the edge with the ball quickly. This is very similar to how West Virginia uses their jet sweep out of pistol diamond to get speed to the edge quickly. If you've been paying attention to the previous cutups, you've probably already seen a few TDs scored off of this concept.
If the defense stacks the box anticipating run, Mazzone will run playaction. They like the fade if they get 1-on-1 coverage with either their big 6'4" WR or their quick little guy and either throw it up or hit the back shoulder fade. You've got to think that they'll put Joe Fauria out there next year and throw it up to him if they get him singled up on a corner. This was the playcall in the Vegas Bowl on the 100+ yard pick-six by Boise State. They had the look they wanted, no safety help and WR all alone, but the WR didn't get open. They'll also do things like sneak the FB/TE upback out of the backfield (Anthony Barr would probably do well here as he did this last year) or the WR on the post, like you get with an I-formation playaction passing game.
Mazzone will run QB sneak for very short yardage - just shift the QB under center and have him fall forwards, nothing special.
The pistol diamond stuff was fairly limited and situational from what I saw. They like it in the red zone and when coming out of their own endzone. As it's fairly new I'd expect it to develop a bit more as time goes on. It adds a new dimension for spread teams to operate in a pseudo-2 back look and get out of their regular 3x1 or 2x2 4WR stuff. It's a cheap change-up as you don't have to install anything completely foreign to your team, but you still force the defense to play you as if you've got a couple backs in the backfield.
Mazzone still uses it to put bodies inside and run downhill, but still forces the defense to think about defending the entire field sideline to sideline with constraints like the swing to the motion man combined with the inside zone or playaction to the deep middle, fade, and flat. As you can see in the cut-ups below, they're looking to run inside whenever possible but when the defense leaves CBs singled up outside or stays bunched in against motion, they'll hit the quick swing route to get to the edge.
West Virginia is probably the best I've seen with running stuff out of the pistol diamond, as they've mixed in stuff from a more traditional 2-back running attack that works in downfield playaction. They've gotten away from the Mike Leach stuff that relies on short passes and crossing routes, and have gone to looks with more backs in the backfield and downfield vertical routes off of their PA game. If we really wanted to get more "pro-style" as Mora said when he got hired then I think this would be the way to do it, with what WVU is doing as a model.