Ergas is the fourth member of the signing class.
Season ticket renewals will begin in June.
Flynn was named the Associated Press's State Player of the Year.
Four Cougars earned Pac-12 All-Academic accolades.
WSU falls to Colorado, 80-56 at Las Vegas.
The junior forward earns the honor for the second-straight year.
The 12th-seeded Cougars take on No. 5 Colorado Wednesday at 2:40 p.m.
Tip is scheduled for 2:40 p.m. Wednesday at Las Vegas's MGM Grand Garden Arena.
Josh Hawkinson tallied 23 points and 17 rebounds for WSU
Cougars and Huskies meet at 8 p.m. Wednesday on ESPNU.
The Cougars will conclude their regular season Wednesday at UW.
Sunday's 3:30 p.m. tip will be televised on the Pac-12 Network.