Chris, I believe that you have hit the problem on the nail. He has a tremendous serve when it clears the net, but the ball toss is not consistent. Get that right and he's on the way.
I still go along with Andy's comment way back, and I keep repeating it time and again ad nauseam, that he feels that his best times will be between the ages of 24 and 27. This is where he is. Let's be patient, observe with delight and not get too ahead of ourselves.
I can't understand why he can't get the ball toss right either. If nothing else, surely he must be able to see what he's doing on video? It seems to me that he's frequently throwing the ball just a little too far in front of him, and as a result it either dumps into the net (if he doesn't throw it high enough) or it goes long.
I have heard, though, from those lucky enough to watch him practise, that his serve then is fine. Seems to be that once on court something starts misfiring somewhere, and that unfortunately applies to the rest of his game when Mr Tragic turns up.YESSSSS!