Overrated I won't even take a stab at. Everyone's World Golf Ranking is pretty accurate and that's how I consider golfers' "ratings."

Next big things:

Hunter Mahan (future top 10 in the world)
Camilo Villegas (ended up the FedEx Cup palyoffs with 3 top 10's in tournaments with the strongest field in the world)
Morgan Pressel (takes over the #1 in womens golf in the next 3 or 4 years)

I don't think Adam Scott fits in here. He's already a big thing.