Oh I love this question! As I’ve written about a little bit I’ve been calling this defense the “Double Nose”, because it’s really like having two nose tackles from the old 3-4 in the middle, often two gapping, while trying to free up five other linebacker types to make plays. So in some ways you could also call it a 2-5. You’re right too though, 75 is a huge part of being able to run this defense because of the way he can control two gaps.
Here’s a good article about what the Pats did last year on defense from Chris Brown of SmartFootball.com. But last year was a lot closer to a traditional 4-3, even though they were mixing up gap responsibilities. They still do that but the biggest personnel switch has been going from someone like Shaun Ellis who is 6’ 5”, 290, to someone like Rob Ninkovich who is 6’2”, 260 at left defensive end. Ninkovich is really the key to this whole defense working against the run because he’s smaller than a traditional 4-3 defensive end. Usually the left defensive end spot is the place that gets run at the most.
Nink held up well against the run against the Titans, and though his pass rush numbers might’ve suffered a bit, he did everything they needed him too.
Ultimately the Patriots defense has evolved to this because in the modern NFL you need more athletes on the field, to not only get after the passer on every down, but also to deal with the numerous kinds of evolving threats that are becoming more and more common place.
So yes, I do think we could see more teams trying to emulate this style, but you really must have dominant nose tackle types like we have in Wilfork to make it work. Kyle Love’s improvement has also been a huge factor in making this defense work, and I’m sure we’ll see plenty of Ron Brace in there too before it’s all said and done.