I'm trying to change my takeback on my one hander. I used to pull the racquet back without using my left thumb with a wide and relaxed stroke but I was having problems when I had to handle some pace. Under pressure my stroke became unreliable and I would spray shots left and right. Today, following a pro advice I started to also use my thumb on the takeback and it somehow shortened my backswing and I fell my backhand became more compact and stable but somehow it feels unnatural and stiff. Anyone with the same problem or with any advice?