As a double bender, i have never understood why Fed and Nadal both uses straight arm forehands till today. I have tried to use straight arm today, and surprisingly i had a way better lag effect than ever. Never understood "Pull the racquet butt towards the ball" thing but now it seems possible for me to do that with a straight arm. Also, first you need to turn your shoulders to make your arm straight, so it allows a more efficient use of kinetic chain and SSC. Do you think i should change to a straight arm ?