This is an outstanding thread. The OP was great, and everything that I wanted to say in response to it was already stated by someone else. Yes, Clemson showed what a top shelf defense can look like in the current age of RPOs, etc., but don't leave out all of the moving parts that made that happen. Here's what I saw:
- Top-shelf talent everywhere = Their entire D-line will play in the NFL, and most of them will be 1st round draft picks. They have D-linemen in such depth that their best DT didn't even play because of the positive drug test. They were rotating bodies in and out, and every one of them was a beast. They have talent at every level of their defense, but that D-line is the sort that DCs dream of having just once in their lifetimes. The LBs and DBs are not all NFL type players, but they are solid at the college level, and several will play at the next level. To beat a well-coached, disciplined, talented offense, you have to have talent; to dominate them, you have to have NFL-caliber talent.
- Scheme = Everybody is praising Venables, and he deserves it: that was a masterpiece of a game in defensive scheme. I haven't watched Clemson enough to know for certain, but judging by the confusion on the Alabama side, Venables unleashed some new looks in that game, including some very complicated zone blitz concepts. As has been already said, McBride dropped that same bomb on Wuerffel, Spurrier, and Florida in the '96 Fiesta Bowl, and it blew up their offensive scheme. If zone blitz schemes were easy to install and execute, you'd see it all of the time; there's a reason why you don't: it's almost impossible to install and execute, especially with levels of different wrinkles and packages. I don't know how much Clemson has done that in the past, but it's kind of the Holy Grail of defensive schemes because it takes a difficult combination of talent, smart players who can adapt on the fly, and enough mastery of the basics of playing your base defense that you can move people around like pieces on a chess board, and everybody knows how it affects their responsibilities/assignments. If you can't rotate your blitzers and disguise the coverage, you'll get torn apart. If you run it consistently, the offense can gameplan it and attack it. There has to be a level of unpredictability with new looks and new wrinkles for it to work like that.
- Preparation = How about how they defended that fake field goal? Did you notice that Clemson kept their defense on the field instead of putting in the special teams unit? Did you hear that Swinney and Venables went all of the way back to 2002 LSU film to see how Saban might run a fake field goal? That takes behind-the-scenes staff people to go through a lifetime of film and find what you want for you, prepare the film, break it down, and serve it to the coaches on a silver platter. If the Clemson staff did that for a fake field goal, you can bet your @$$ that they did the same with potential fake punts, trick plays, etc. When your opponent has prepared for every possible variation and wrinkle that you can throw at them, you better hope that you have better players than they do. Fwiw, this is also an example of why coaches burn out. You simply can't prepare at that level for every game because there aren't enough staff members, physical resources, film archives, and hours in the days to do it all. When you have a month--or probably in this case, a year--to prepare for everything, it becomes possible. I've yet to meet a coach who isn't haunted by a game that his team could have won if only he'd been better prepared, which almost always means sacrificing your life outside of football for some period of time to make it possible to be that prepared.
- Stability and consistency matter = Whenever you bring in a new coach, you have to either adapt to his vocabulary, or he needs to adapt to yours. This is a lot more difficult than it seems unless a coach has played or coached in a variety of systems. For example, Osborne used a numbering system for his offensive gaps that I'd never seen before, so I looked into it and found out that he had kept the same system that Devaney's people had brought with them from Wyoming, which was based on an old Wing-T system. Most modern offenses have a simple system where you count gaps out from the center, and odd numbers are to the left, and even numbers are to the right. Osborne's system started counting from left to right. Different backs and receivers have different names and alpha-numeric abbreviations: the X, Y, and Z of the West Coast offense came out of Sid Gillman's system from the 50s, but other coaches number their guys, and sometimes a Y is ALWAYS a Tight-End, but sometimes a Y is the receiver who is a TE or a flexed TE or an H-back or .... You get the idea. Defensive schemes aren't as complicated as far as the numbering of techniques for D-linemen, etc., but the language and terms are still complicated and varied from system to system and coach to coach. Clemson didn't have that problem, and that freed them up to do more with what they already knew.
- The right kind of experience matters = Swinney and Venables are in the heart of their prime years as coaches, and it's not the same for defensive versus offensive coaches. They've been around the block to have picked up lots of ideas from various places, but the ideal DC has had to play and coach in multiple systems when first starting out, but then has settled into one specific defensive system for the rest of his coaching career: you can teach an old DC new tricks, but you don't want to try and turn a hunting dog into a sheep dog. If a DC runs the same system for a decade or more, and he plays against offenses that are wildly varied, he'll know the strengths and weaknesses of his system better than anyone else, and he'll know how to take advantage of personnel matchups and blitz packages when they present themselves. Venables identified something in the way that Tua was doing his pre-snap reads that he could make into a vulnerability, and he attacked it. Other coaches in other systems might be able to attack the same thing, but they would have to do it in different ways, and it would have different results. Meanwhile, Swinney recruited, signed, trained, and started a 19-year-old QB to win that game. Yes, he's a great QB in almost any system, but Swinney has been shedding top-notch QBs left and right because he knew what he needed, and he knew when he found it. Swinney and Venables are still young and cocky enough to believe that they could do all of the above and have the confidence and commitment to carry it through. If either or both were 10 years older, I doubt that they'd be so willing and eager to adapt like that. If they were 10 years younger, they wouldn't have known enough to do it.
- A "great defense" doesn't mean what it did = Clemson did NOT "shut down" Alabama's offense. They created turnovers, made key plays at key moments (including sacks and tackles-for-loss), and they stopped drives in the red zone. Alabama won Time of Possession. Alabama stacked up a ton of yards and more than a few big plays. Clemson's defensive scheme was built around the principles of forcing turnovers, limiting points whenever in the Red Zone, and taking risks with the knowledge that their offense would score points to make up for mistakes and big plays. Fwiw, the exact same was true of Nebraska against Florida in the '96 Fiesta Bowl.
If you take all of the above and hold it up to Nebraska now, we really are in a good position for the future. Yes, our defense was awful this past year, but I'm tired of hearing people complaining about Chinander. He did a lot with what he had, and by the time he gets the people he needs, he will be getting closer to that sweet spot of consistency and experience, too. I firmly believe that the same people who hate him now will whine the loudest when he eventually moves on. If you liked what Clemson did to Alabama as far as exotic blitz packages, you should love Chin's defense because he's got that already built into it. What he doesn't have is almost everything else that I listed above.