Nobody is suggesting forearm horizontal or anywhere near that, so that's a big red herring. What i'm saying is that almost vertical forearm is probably fine, (And arguably ideal?). Would you say that ideal is completely 100% vertical? Or "almost vertical"? By almost would you say offset by 0-10 degrees? And would 20 degree offset be too much in your view? And if you agree re that, that almost vertica eg 0-10 degrees l is fine or ideal, then from a pedagogical perspective there could be an argument either way. vertical, or almost vertical or both . Also I think you are mixing forearm and racket shaft.. Also you are mixing talk of forearm vertical and racket vertical. They are very different things. If the forearm is almost vertical, then the racket shaft could be vertical(And I think that's good). If the forearm is vertical then the racket shaft won't be(and that may be not so ideal).