Kevin McHale started working with Kevin Garnett when the latter was in a relatively young, raw state. The Houston coach is getting Dwight Howard at a very different time, when some believe the center is set in his ways. But McHale, as perhaps the greatest post scorer the game has known, doesn’t see it that way. “You’re a finished product the day you retire,” the Celtics legend said before his Rockets entry in the Orlando summer league took on Philadelphia yesterday. “Up until then you’re always doing something. In the NBA you are always evolving and changing. I think Dwight is in the process of evolving and changing. He said he feels way better and healthier than he has. His back feels better. I just anticipate him coming in and being the most dominant center in the league.” Some coaches and general managers are on self-imposed gag orders about their new additions due to the NBA’s contract moratorium, which ends Wednesday. Not so with McHale. He simply can’t wait to get started.