I’ve watched a handful, particularly when I was living (studying) in the states, and no doubt it is a game of strategy, and no doubt I don’t understand it well (as I mentioned). I hesitate with your strong endorsement of the intensive mental stress of it however, particularly when compared to the sports I mentioned, particularly Union, which lacks the long pauses and set pieces of NFL and requires more dynamic and on-the-fly thinking without coach or other input. I’m not saying it’s less than, but to use an analogy, I think for example Union is like the US Marine Corps (browsing their wiki article last night) where the outcome is the goal with the methods to be determined by the players, whereas NFL seems to be a continual discussion of strategy and set plays with sideline input, something not overly possible in union