In one respect, Klay Thompson’s departure from the Golden State Warriors — now that the legendary shooter has agreed in principle to join Dallas on a three-year, $50 million deal with the Mavericks, league sources confirmed to Yahoo Sports — began last offseason, when the Warriors and Thompson could not agree on a contract extension. Golden State offered Thompson a two-year deal, sources said, in the ballpark of $50 million of total value that was roughly half of the four-year, $100 million commitment the Warriors handed Draymond Green in free agency.