Good post, and thought provoking!
I'll give my thoughts, but you know my biases, and are free to grade on a curve, so to speak
1) I'm going to do something cruddy and re-challenge your challenge. Paul Johnson is, in my mind, not the be-all and end-all as a head coach. I DO think he might be the be-all and end-all as an offensive coordinator, though, but his failure to ever get an above average defense at Georgia Tech is his failure. The notion that the two are anything other than VERY tangentially connected I think is a falsehood. I fail to see a reason that Paul Johnson couldn't have an ounce more charisma, and hired Nate Woody 4 years earlier, and not had 1 standard deviation better defenses. That offense is going to hold down OFFENSIVE recruiting, and yeah there is maybe a SMALL degree of collateral damage from coaches saying "you don't want to practice against that, you'll get your knees hurt and it won't prepare you for the NFL", but a good recruiter/defensive coordinator tells prospects "you're going to be playing against the scout offense, and you're always going to be playing from ahead, which means lots of INT's".
Now, obviously that speaks to point 2 of your post, which is "why not have it all?"
Well, to my mind, you HAVE proven that you could succeed with the first model, and you HAVE NOT proven that you could succeed with the second model.
In the modern era, you have proven that you can have consistently excellent offense, and consistently "good enough" defense, you just haven't had them at the same time. You had "good enough" defense under Gaily, and you had excellent offense under Johnson. Now, maybe Paul Johnson himself wasn't the guy to recruit/coach a good enough defense to be "good enough", but there's no reason Jeff Monken, for example, could not be.
It was ALWAYS weird to me that Johnson hired "bend but don't break" defensive coaches, given that in my mind a high risk/high reward defense is a much better fit with Johnson's offense. I thought Woody was a GREAT hire for that reason, and I thought they were going to do really good things together at GT.
Well, I was right..... sort of. He's gotten together with Monken at Army, and those guys are a handful, despite having the worst football talent in America.
So, you've proven all the pieces can work at GT, you just never had them at the same time consistently enough.
What you have NOT proven is that you can consistently recruit and retain top 20 recruiting classes at GT.
Remember, when you're running the same schemes everybody else is (and I assure you, GT is. Their offensive schemes are just ABSOLUTELY bog-standard modern spread offense), you fail or succeed on A) teaching ability and B) recruiting (and really, more on recruiting). If you get top 35 classes, you're going to get top 35 results.
If top 35 results are good enough for you, then top 35 recruiting classes are good enough.
I assume you want top 20 results, which means top 20 recruiting classes, and (per 247) since the year 2000 (which is a relatively arbitrary measure, I admit, but it captures the sort of "modern era" of recruiting, with kids beings scouted since they were freshmen and the internet and all that jazz) you have had top 20 recruiting classes in:
2000 (number 19)
2007 (15)
...and that's it.
Now, that 2007 class came with Collins as head of recruiting, but he's had 2 classes as head coach so far, and they've been numbers 27 and 39.
The question this begs is: Is Collins a GREAT recruiter or just a competent one?
If Collins is a GREAT recruiter, then you're in trouble, because the number of people who are GREAT recruiters AND above average x's and o's guys is relatively slim, and they usually coach at places like Georgia, not places like Georgia Tech. If Collins is a GREAT recruiter, and what he can get at GT is top 35 classes, then it's really NOT a sustainable model, because there are relatively few GREAT recruiters, and your next coach isn't likely to be one, because there's no moneyball inefficiency there. Everybody wants a great recruiter, so they're really hard to come by, and the ones you can get are just statistically unlikely to be great x's and o's guys, too.
There IS a moneyball inefficiency with guys like Monken, because of the "undesirability" of the system. You can get better x's and o's results than your "expected value" at your school.
If Collins is just a competent recruiter, though, then maybe you're cooking something there, bbecause you ought to be able to find a competent recruiter who is a good x' and o's guy. If GT really CAN compete heads up with the rest of the ACC in recruiting, and doesn't require EXCEPTIONAL recruiting talent to achieve "slightly above average" recruiting results (which is what you're getting now), then good.
I'm just saying one model has been PROVEN at GT (in separate pieces) and the other has not. That said, Flight was always possible, we just didn't know it until the wright brothers came along. So maybe Orville Collins will be remembered similarly.
JJesus, sorry for the rambling, war and piece length answer, but it's sunday and I'm puttering around the house sore from doing yard work yesterday and I came back to this like 4 times, haha