As of today Tiger is not the best in the world, and won't be after the weekend either. He'll be competitive in the Masters, but probably finish somewhere in the late teens.
Nick Watney is probably the best in the world right now, though a bit of a lesser known golfer. He's got total game and hits the ball high. You can't compete in todays majors with a low ball trajectory. He's accurate off the tee, has a fantastic short game, and really handles the majors well.
In this tournament it's all about Mickelson. He owns Augusta, and it seems to be the only place he can handle mentally. 1st, 5th, 5th, 24th, 1st, 10th, 1st, 3rd, 3rd, 3rd, and 7th since 2000 is about as good of a majors record as you'll ever see.
For this weekend the guys to watch are Mickelson, Watney, Kuchar, Kim, Mahan, Snedeker, Stricker, and...Fred Couples. I'm telling you, keep an eye on the old man.
As for Tiger, he's fine. There isn't a thing wrong with his swing, and it's as fundamentally sound as any I've ever seen in 15 years as a class A-1, A-4, and A-6 PGA professional. Tiger's issue right now is all about feel, and has little to do with confidence and technique. The swing doesn't feel right, the putter doesn't feel right, and he just doesn't feel right on the course. It happens to ALL golfers, but all golfers aren't Tiger Woods. Tiger is the PGA equivalent of the Dallas Cowboys, and everything he does is amplified. Lots of pros struggle with dips like this in their career - Jim Furyk, Adam Scott, Ernie Els, Retief Goosen, and Geoff Ogilvy are guys just off the top of my head that have suffered through similar situations without 1/2 the fan fair.