Some cores are bad matches with some coaches. I think that Wolves group (KAT, Wiggins, Lavine, Rubio) would have done a lot better with a space and pace coach like D'Antoni rather than a slow grinding style. They were uber athletic and their PACE rating over the Thib years were 25th, 24th, and then 14th (fired mid season and improved in the 2nd half).
You can always bring in veterans to do the dirty work around the talented kids later rather than trying to turn thoroughbreds into plow horses and then getting angry at them when they're not good at it.