Well no, an existing professional American football player has no chance of switching to being a professional soccer player. Nobody can simply switch at that level. You have to have cultivated the skills over a long period of time to ever have a chance at competing at the highest levels.

On the other hand, I can’t imagine the guys that ended up being cornerbacks, wide receivers, safeties, or even halfbacks couldn’t have become soccer professionals given the right culture, training, and desire growing up. Sure, linemen, tight ends, and fullbacks aren’t built for soccer.