That's it in a nutshell, it's makes no sense to say the early 90's teams were great due solely to Jimmy, even I don't say that. No doubt Jerry had input, if for no other reason than what's shown in Diehardblues comment.
I just have a hard time with the opinion that Jerry had a large part in the process, from nearly everything I've read and heard Jerry gave Jimmy nearly unfettered control over personnel matters, simply because Jimmy had spent 25 years in football and had the knowledge, experience and contacts that you simply must have to be a successful NFL coach. (And no doubt also why Garrett hasn't been that successful as head coach).
I don't care how intelligent Jerry was/is, he didn't have that. Albert Einstein was no doubt a super genius, but would you want him doing brain surgery on you? Of course not, he didn't have the training and knowledge to do that. Smarts can only carry you so far...