Blatt also said that is why people shouldn't listen to ESPN talk-show host and analyst Stephen A. Smith, who repeatedly told viewers that Doncic shouldn't be considered the frontrunner for NBA Rookie of the Year.
Smith also doubted Doncic prior to the draft.
"I told everyone he was the best player in the draft. Stephen A. Smith is clueless at basketball," Blatt told reporters during a conference call Wednesday. "(Doncic) is hands down the best player in the draft."
Blatt is now the coach of Greek club Olympiacos and was speaking during Calcalist's Forecast 2019 conference in Tel Aviv.
Meanwhile, Doncic is having a fantastic season for the Mavs, playing both the shooting guard and small forward positions. Through Tuesday, he is putting up 19.6 points, 6.5 rebounds and 5.0 assists per game.
When it comes to the top rookie conversation, Smith has primarily been in the corner of Phoenix Suns center Deandre Ayton,
Ayton is also putting up impressive numbers, at 17 points per game with 10.9 rebounds and 2.2 assists.
Smith had not responded to Blatt's comments as of early Wednesday evening.
Blatt coached the LeBron James-led Cavaliers to an NBA Finals appearance in his first season, but was fired midway through the following year. The Cavs then went on to win the lone championship in franchise history under coach Tyronn Lue.