Answer
The correct answer is Mike D'Antoni. In 2008, Dragić was traded from the Phoenix Suns to the Houston Rockets. At the time, D'Antoni was the head coach of the Rockets. In 2015, Dragić was traded from the Rockets to the Miami Heat. At the time, D'Antoni was the head coach of the Heat. So, D'Antoni traded for Dragić in both Phoenix and Miami.