wanted, some opinions from players who are knowledgeable and who have been around the block. Is it a must to set the wrist (also known as the L position) on the slice backhand or is it an option. Seems like Fed sets his wrist on both the slice and topspin BH. Second question Is it a must to keep your racquet and forearm at a 90 degree angle on your forward swing. I would think if you maintain the right angle between forearm and racquet it would eliminate alot of variables. Thanks a bunch.