Not exactly true. While diving correctly might typically stress the front muscles it is completely possible to injure any muscle by diving. Especially if you land awkwardly or recover awkwardly. There is no typical diving injury. So the idea that you can eliminate diving as a possible source of this injury on the basis you sight is silly. I don't know what caused his injury but I not prepared to eliminate any possible factor nor am I willing to leap to the conclusion it's due to the heaviness of his racquet. It's not like he is new to heavy or head heavy raquets. I will agree with you in that I wish for his speedy recovery.