Were those pre salary cap days teams really the best they could be with little to no holes or did they just follow the "blueprints" of the era?
I remember no one really knew what to do with sub 220 pound RBs who could catch and run in space prior to like 1996 or so. Now look at what teams are doing with those kinds of weapons. Imagine if someone had thought of that in say the '80's o 90's and just victimized the jumbo sized run stopping LBers of the era with wheel routes and RPOs? I mean we saw a bit of how effective that could be with Roger Craig, but I remember few other teams wanting to do that because running the ball and imposing your will with a 225+ pound battering ram was the agreed upon template at the time.
Did no human males grow to 6 feet 4 and around 240 Lbs that could run and catch before? Why did it take until the mid 2000's for coaches to be be like "Hey - I bet that kid could do some serious damage at TE!" I'm betting the main reason has something to do with "blocking" and "totally crappy at it".
I totally acknowledge that the salary cap and league rules currently place some severe restrictions on what teams can and can not do. But there is always something and over its entire history, the NFL as a broad collection of teams has demonstrated a consistent tendency towards conservation and being slow to innovate. Typically some other venue serves as the incubator for the innovation and only after it is proven does an extremely risk averse NFL incorporate the new idea(s). People in the NFL said the 3-4 wouldn't work. Spread concepts couldn't flourish. Scatbacks. Speed WRs. Etc...Etc...
The next innovation is out there. The NFL just needs to recognize it and learn the lessons. For instance, everyone wants to laugh at Chip Kelly. And for much of it they are right. But again, the NFL learned the wrong lessons from the Kelly disaster(s). Don't throw everything out, just the stupid bits that don't work! But pushing the pace on offense (Pats have had a few SB seasons playing at a manic pace on that side of the ball), running multiple plays out of the same basic formation (many good offenses do some of this) and whatever he did to make bad QBs look like MVPS (with the dearth of great QBs you would think more teams would get on board) all worked. These ideas and elements of the overall Chip Kelly crapfest can be salvaged and successfully applied in other situations, but instead most of the NFL just sits back and is like "LOL! Gimmick Offenses are dumb!"
Currently, almost every NFL team is struggling mightily to defend "college offenses". The rise of run pass options, spread concepts, pistol type stuff - might be the story of the 2017 season. Gee...if there was only an entire level of football dominated by those offensive concepts and full of defensive strategies for dealing with them. I think they play on several Saturdays each fall. For crying out loud, the same concepts are prevalent in most big-time high school programs. Think none of those coaches have any worthwhile ideas? Meanwhile, defensive coordinators around the NFL are seen weekly standing on the sidelines with no answers while their team gets torched.
These and other reasons are why I have no patience for the salary cap and rules make everything too hard argument. It isn't that it isn't true it is just that it is (to me) evidence of a larger problem.