Some rackets, such as my APD, are closer to a circle shaped. I call it a "fat" racket. But most other rackets it seems are more oval shaped, "thinner" although I don't know if they are actually longer. What is the purpose in these racket shapes? What are the pros/cons of the different ones? I'm starting to feel like my APD isn't working for me and I starting to think about what else I could look into. Also, while on the topic, what is the benefit of extended rackets? Like the plus versions of rackets that are longer.