George Karl, who won the NBA’s Coach of the Year Award after guiding Denver to a 57-25 season, has been let go as coach. Yahoo! Sports’ Adrian Wojnarowski first reported the news via Twitter:
In final year of deal, Karl was pushing for a contract extension, and ownership wasn’t prepared to give it to him, source tells Y!
— Adrian Wojnarowski (@WojYahooNBA) June 6, 2013 
Source: NBA.com