Once upon a time, we’re told, NFL players were tougher. They played in cardboard-thin padding with helmets made of thin plastic and no facemasks. The stadiums were outdoors, and they ran 100 yards — uphill each way — in 20-degree weather. And they liked it. Quite a bit of this was, in fact, true. Cleveland’s old Municipal Stadium, for instance, featured “grass” that was little more than painted, frozen dirt by November. (That’s part of the reason why the original Browns are now the Baltimore Ravens, by the way.) The joke artificial surface known as “Astroturf” made many a knee surgeon a mill…
