The best combination is insane talent, opportunity, and incredible work ethic. When you find those guys, you'll find the ones that were always going to be on Tour. That would be Davis Love, David Duval, Tiger, Nicklaus, Greg Norman,
Then you have the ones who made it on B+ talent, opportunity, over the top work ethic, golf brains and the fact that they were the best chippers and putters in the world. Curtis Strange, Justin Leonard, Brad Faxon, Tom Kite, Zach Johnson
Then you have the ones that are just true golf geniuses, naturals per se. Seve, Johnny Miller, Lanny Wadkins, Fred Couples, Rory Mcllroy, Phil Mickelson, etc
Then it gets cloudy for me, you never know what's gonna put a guy over the top and get him to the big leagues. I have a kid right now in the Zach Johnson mode who has this incredible tunnel vision and work ethic. I think the general consensus in our area is that he's just a really good player. But experience has taught me with his skill set and opportunity and single minded ness, I see no reason why he wouldn't have a shot. I don't dismiss anyone after seeing "can't miss guys" miss...and these dinkers and one way shotmakers who can putt make it.