What I found in my game is: when my opponent has strong stoke, the ball I hit back tends to be stronger as I use his/her power and counter punch it back. However, if the opponent hits ball weaker and no pace, and I try to generate power on my own, it is not as good, and my shot is weaker. So I have to hit angles and more rallies to wait the opponent to make mistake (or myself) or build up advantage slowly. sometime very tied although feel pretty good. Try to increase power for the groundstroke. so my opponent can not deal my stroke easily and hit to the cross court. So I have more choice. I am currently using Babolat APD, should I switch to a thinner beam/smaller head size racket?