Have you played with it and compared it to pure wood racquets? I have. A decorative outer layer of graphite doesn't add any significant stiffness to a racquet. Further, your premise is false as seen in the video from his 1974 match with Amritraj. Borg was always a huge hitter. Lendl's racquet, by contrast, was graphite and kevlar, much more rigid than Borg's racquet.