Most overrated and uderrated directors. It's the "in history" that makes the question difficult. However, and I mean this with no disrespect, since I like him very much, I think Ron Howard has had one of the most overrated careers. I liked Splash, and I liked Night Shift, but not much beyond those. And his most critically lauded films put me to sleep. Kevin Costner, Redford - most of the actor-types. Mel Gibson. Their film just don't do it for me, and yet they win awards and kudos.
Underrated, there are so many: Anthony Mann, certainly. Budd Boetticher. Delmer Daves. Frank Tashlin.