Golf is a tough sport to dominate. I think that's what made Tigers first 10-12 years as a pro so impressive. Unlike other sports, even other individual sports like tennis, in golf you don't go up against one opponent at a time. You go up against every other pro each tournament. As a pro golfer, you can outplay the 20 next best golfers, and a rookie golfer or a middle of the pack pro has the weekend of his life and beats you out. You have to beat everybody to win tournaments.
I do think a lot of it is mental. He lost his edge, his mojo. He lost his image and I think it's affected his confidence. He's still relatively young enough to win a couple more majors but I wouldn't bet the house on it.