As usual, all the pre-tourney hype seems to surround Tiger Woods and Phil Mickelson. I don't think either of those will win.
There's no way any mortal dominates a course in two consecutive weeks the way Woods did at Firestone in winning last week's WGC Bridgestone Invitational. He's got to come down to earth at least a bit.
It's been five years since anyone (Padraig Harrington, 2008) won consecutive majors, so picking Mickelson to back up his Open Championship with a win here seems to be a long shot.
It's been 13 years since anyone won back-to-back PGAs (Woods, 1999-2000), so picking Rory McIlroy isn't in my line of thinking, either.
There's so much balance in golf right now it's nearly impossible to pick a winner. I'll take the field and, to further narrow it down, make it a first-time major winner. Of all the majors, the PGA has a track record of producing more first-time, lesser-known winners (see Shaun Micheel the last time it was played at Oak Hill in 2003). Maybe Hunter Mahan or Bill Haas or Dustin Johnson. Who knows?