Boston Celtics star Isaiah Thomas was unhappy with Brad Stevens being left off the list of finalists for Coach of the Year.

The Celtics guard had some pretty harsh criticism for the panel of NBA media members who determined the finalists for the award.

Thomas used a question about potential free agents coming to the Celtics to vent about the omission of Celtics coach Stevens from the list of the three coaches who were selected as finalists – Miami's Erik Spoelstra, San Antonio's Gregg Popovich and Houston's Mike D'Antoni.

"I haven't [talked to any upcoming free agents] yet. I was focused on trying to get as far as I can in the playoffs. And also focusing on why Brad Stevens ain't in the Coach of the Year conversation," Thomas said Friday during his exit interview with the media, via USA Today. "That's BS.

"I was thinking about that the other day. Like, we're the number one seed in the East, and everybody in the world thinks we're half as talented as anybody in the NBA. It's weird he's not even in the conversation. That's crazy.

"He should definitely be in the running, and if you ask anybody in this league, he should definitely probably be the Coach of the Year."

The Celtics had the best record in the Eastern Conference and advanced to the conference finals before getting ousted in five games by the second-seeded Cleveland Cavaliers, who are the defending NBA champs and in the NBA Finals for the third straight year.

Popovich is the favourite to win the award, but should it go to Spoelstra, he would be the first coach since Doc Rivers in 2000 to win the award with a .500 record and no playoff appearance.