Rory McIlroy just changed to it. Jordan Spieth has been using it. What is it? Left hand low (for right handed golfer) or the cross handed, cack handed putting grip.
Why? Rory said that he felt that his right hand was just too involved in his stroke. Cross handed forces the putter to rely more on the pendulum dominant stroke.
We have compiled some of the better videos on how to master this putting method.
Good luck on the putting greens!