Ted Williams is perhaps the greatest pure hitter in the history of baseball, and also maybe the smartest. So many of his insights now dominate the game — the uppercut swing, the understanding that walks are good, actually, and a certain forgiveness for defensive lapses if the stick is good enough.
The most interesting insight Williams had on hitting, in my eyes, is the way he envisioned the strike zone. The rulebook might delineate a pitch in the strike zone as a hittable pitch, and an umpire might call a pitch a strike, but that doesn’t actually mean a hitter could make good contact with it.