A very high percentage of the top players would have starred in any era
Are you going to tell me Mark Spitz would flop as a swimmer today? His gold medal times don't even qualify for the finals.
Obviously, the training methods and knowledge are vastly superior today. The best athletes of the previous eras would have taken full advantage and become bigger, faster, stronger and every bit as good.
I think the best post in this thread concerned the oldtime secondary players who would now be on the bench, or out of the league. Exactly. You're never going to see a Tim Foley starting at CB in the NFL again. The rules of that era basically allowed DBs to tackle the WR before the ball was released. Miami took advantage of that better than anyone until the Isaac Curtis Rule.
Frankly, I think pass interference is an absurd penalty that should be all but eliminated. If you can smack a running back while he has the ball, why not flatten a flimsy WR before the ball arrives? Sorry, but I've never understood that wimpy reasoning, that the time period when the ball is in the air is somehow magical and no one can be disturbed by a naughty bump. I guess they're trying to avoid more Darryl Stingleys, but to me it detracts from the game. I want the most destructive teams to prevail, not someone with a dainty QB.