True but dudes like Adrian Wilson and James Harrison wouldn't have been in the shape they are now if they'd played back then. Back then those were the guys in the best shape. The meanest toughest SOB's. They didn't train from the time they were 5 to play football. No pee-wee, no physical regimen the way they have now. Now they come into the league looking totally ripped and that wasn't true back then. Back then you did it on your own because you didn't make sh*t for cash anyway, and you worked in some meat-packing plant or the docks and played football in your spare time.
It's impossible to mix era's. The way I look at it the guys like Lane were the Adubs of that era and you can't go back. I doubt Lane could come forward either, but there are other guys who could. Like I think Otto Graham could, if trained from beginning to end (mentally) could still play today's QB position even in the physical shape he was in then (which was superb for the time), but I doubt a dude like Favre could play QB back then when they were allowed to kill ****'s.
Adub and Harrison wouldn't necessarily have been badass then. Not even if they were in the best shape for dudes of that time. They certainly wouldn't be beheading dudes and sending dudes to the hospital the way people think. You can't take the shape they're in now and transport it back 60 years.
And as for Rugby, I like watching me some Rugby, but there's no comparison whatsoever to the NFL. Rugby is a grind game. There is no Rugby player on this earth who could potentially compete in the NFL all game long. He'd get too gassed and wouldn't be quick enough or fast enough in the short to medium-game (not to mention the long game). NFL dudes run 100 yards on kickoffs and cover long passes and go laterally at high speed with superb athleticism. That being said, you could take the best lineman in the NFL and put them on a Rugby team, teach them the rules, and they would own Rugby, just own it. They may even like it. NFL lineman aren't afraid of broken noses or aches and pains, let's get real. NFL lineman can move laterally over a short distance much better than any Rugby player. There's no comparison. They can run laterally faster and pursue faster and they're huge and tough. There's no comparison to the training these guys get in the NFL. And if you don't like using lineman, you can use a FB or a RB like Jones Drew. No comparison. Bar none.