Jon Rahm survived a final-round 75 at the Memorial Tournament a year ago while cruising to a three-stroke victory over Ryan Palmer. That didn’t happen this weekend when he exited the same PGA Tour stop with a six-stroke edge and just 18 holes to play in the most unfortunate development for a leader since Hunter Mahan in 2013.. Hunter Mahan quit the RBC Canadian Open with the 36-hole lead

