That is what I mean when it comes to Simmons lacking the alpha-mentality that other NBA stars have. Giannis is the complete opposite in that he literally doesn't care if he airballs a shot, or misses his free throws; he is going to try even HARDER if he screws up. How many times did opposing players and fans try and get in his head with the free throw violations? He didn't care, he stayed committed to his routine and in the end, he made 16-18 in the most important game of the season. Simmons' reluctance to shoot, his fear of getting to the line, his inability to really impact the game on the offensive end, are all signs that run counter to what we think of when we think of elite NBA players. They are the most confident people in our society and are never afraid of the key moments, in fact the great ones relish that opportunity.
Simmons has an incredible skillset. He has incredible size, athleticism, ball-handling, court vision and defensive instincts. He is one of the most talented players in the NBA. All of his issues are between the ears, and that is really hard to judge because we have no idea if he will "get it" or if he is just another very talented player who doesn't have the mental makeup to reach his potential. The NBA is filled with people who have superstar talent but never reach their ceilings because they lack the additional superstar drive and attitude to maximize their ability.