No. Rugby requires the ultimate combination of speed, strength, agility - AND endurance. It's a true athletes game.
NFL players are severely lacking in endurance. Lots of fatsos who need oxygen masks. Plus, with their pussy pads they cant dare claim to be tougher sport than Rugby.
If anyone in the US took that sports seriously, they would dominate it. They don't so they don't. Americans only really embrace sports that were created here. That is why soccer , although gaining due to all the immigration, isn't as big. No doubt those rugby players are athletes, but those fat dudes serve their purpose. If you really think those 260 lbs black dudes would be able to last in Rugby if they trained for it, you are nuts.