Wawrinka hands down probably hits his backhand harder than anyone in the history of tennis. Most analysis-es of him will attribute this to his effective use of core rotation, where he opens up to the net more than the traditional one-handed backhand. The closest player I've seen to utilize this is Dominic Thiem but even he rotates to the net less. Why aren't more upcoming juniors and next gen pros who use the one-hander like Shapovalov utilizing this? Is there an unknown drawback that I am missing?