Elleby, the first Cougar drafted since Klay Thompson in 2011, averaged 18.4 points and 7.8 rebounds as a sophomore last season.
A 6-foot-6 lefty known as a disruptive defender, Elleby matched his career high with 30 points in his final game with Washington State, an 82-68 victory over Colorado in the opening round of the Pac-12 tournament. He added 10 assists.
His 30 points were the most for a Cougar in the conference tournament since Thompson had 43 points in a game in 2011.
In his two seasons with the Cougars, Elleby averaged 16.6 points and 7.