"Hit with more spin."

Is a coach who simply says "Hit with more spin" to a skilled young player failing to instill proper mechanics?

A very good local junior suggested that recently when he said he was glad he found his new coach who is much more technique oriented.  The irony is that the kid is already sixteen years old and has very good technique.  That former coach who "failed" to teach the kid technique got the kid to hit very good topspin groundstrokes, so good that I long ago tabbed him "The Assassin" for his ability to rack up 6-0, 6-0 victories over lesser players.  I used him as an example of a kid who seemed to love to hit shots.  He didn't care if he was playing a pusher or a hack or a good player.  He just seemed to relish the chance to unleash those topspin groundstrokes on ball after ball after ball.  It didn't matter how many of those balls came back.  Each one gave him the chance to unload again.  Well, unload may be a bit strong for a kid who was always the skinniest kid in the field.  By a lot.  But he unloaded himself into the ball with all he had.

Now the kid is still winning, but he's doing it by pushing.  He no longer unloads into his groundstrokes.  In practice he goes big, but since he's taller and stronger now, his hitting window is much smaller so he is prone to making errors, especially since he now hits his big shots pretty flat.  

To make matters worse, since this young man now enthralled with his new technique-oriented coach, his emphasis naturally on technique.  Each mistake he makes, and he makes a bunch in practice, he analyzes some minor element of his take back or something.  So instead of learning how to play with the wonderful strokes he already has, he's fixated on minor, largely irrelevant elements of his strokes.

What a shame that his old coach left town and he hooked up with the new guy.  Bad timing.  I hope it turns out well.