(Reuters) - As world number two Dustin Johnson snaps at the metaphorical heels of top dog Jason Day of Australia, the game's leading player has identified the reasons for the American's elevation to the cusp of the global pecking order. After a sizzling summer, U.S. Open champion Johnson enters the Tour Championship starting in Atlanta on Thursday as the top seed and favorite to clinch the $10 million bonus awarded to the season-long FedEx Cup champion, a points race that roughly correlates with the PGA Tour money list. "Every morning he's got a trackman behind him hitting shots, so he knows exactly what his wedges are doing, how far they're going, all that stuff," the Australian world number one told reporters at East Lake Golf Club on Wednesday. More...