Cooper Flagg led the Dallas Mavericks to a 138-133 overtime victory over the Portland Trail Blazers on Sunday, with 21 points, eight rebounds and five assists. But the father of another lottery pick blasted what Portland did with a chance to win with the final possession in regulation.With the score tied at 118-118, Blazers forward Deni Avdija missed a step-back jump shot, with the attempt not even hitting the rim, in the final seconds of the fourth quarter. He had the ball and let the clock wind down before taking his shot. And Spurs rookie Dylan Harper's father, former NBA player Ron Harper, had some harsh words about the last-second decision from the Israeli forward on X."I’ve seen more low IQ in the game then ever if the game is tied or you down by 1 point why would you shoot a 3 for? @trailblazers @dallasmavs game? A low IQ players," Harper posted on social media.Avdija had a great game with 29 points on 50.0% shooting. He added six rebounds, seven assists and two steals. However, Portland (6-7) lost for the fourth time in five games.Most teams prioritize the 3-point shot. The Blazers are fifth in the league in attempts beyond the arc, averaging 41.8. However, Portland has only made 33.3% of its long-range shots, placing it at No. 26.Cooper Flagg and the Mavericks (4-10), however, make 31.3% of their shots from deep. That comes from 34 attempts per game.Cooper Flagg's conversation with Daniel Gafford helped fuel the Mavericks to win over the BlazersThe Mavericks trailed 61-57 at halftime. Cooper Flagg wasn't aggressive in shooting the basketball and only had two points on 33.3% shooting. After the game, Flagg said that he spoke with center Daniel Gafford, which helped him influence the outcome.“He was just telling me to keep my head up,” the rookie forward said. “It wasn’t an incredible first half, but he was trying to help me get involved. Him just giving me confidence and telling me to be more aggressive. When your teammates have your back like that, it helps a lot.Cooper Flagg also told the media how Gafford has served as a mentor to him.“Gafford has been huge for me,” Flagg said. “He’s just such a good guy off the court. Has a great personality, he’s a great person. He’s somebody that I know I can go talk to about anything.”Gafford was also impactful for the entire team on Sunday. The big man had 20 points, six rebounds and three blocks.