Brooklyn Nets superstar Kevin Durant told David Letterman in a Netflix interview that the biggest job for an NBA head coach is "managing personalities."

"I think that's the biggest thing," he continued. "We all know how to play. We all know all the terminology. We know every single scheme that can be. ... Managing personalities, I think that's their biggest job."

Managing egos and personalities is surely a massive part of the job, though many coaches might argue that the tactical components of the position—putting together the right lineup combinations and rotations, drawing up plays that fit the personnel, out-of-timeout plays and in-game adjustments, etc.—are equally as important. 

But there's no doubt that a team's internal culture matters, and head coaches and star players tend to set that culture. 

Phil Jackson would have his Los Angeles Lakers mediate together to feel a greater connectedness on the court, among the Zen Master's many team-building tactics. Gregg Popovich said in 2013 that relationships were the key to success. 

"Yes, we're disciplined with what we do," he told Sports Illustrated. "But that's not enough. Relationships with people are what it's all about. You have to make players realize you care about them. And they have to care about each other and be interested in each other. Then they start to feel a responsibility toward each other. Then they want to do for each other."

Boston Celtics legend Red Auerbach was a master of identifying talent and was a tactical innovator, but he also instilled a team-first mentality on squads that would go on to have numerous Hall of Famers. 

"Individual honors are nice, but no Celtic has ever gone out of his way to achieve them," he once said. "We have never had the league's top scorer. In fact, we won seven league championships without placing even one among the league's top 10 scorers. Our pride was never rooted in statistics."

To Durant's point, every player in the NBA is a baller who has dedicated their life to the game. No team is devoid of talent. But what separates talented teams from champions is how the players come together and whether they buy into the system. One of an NBA head coach's primary jobs, if not the main one, is finding a way to get that buy-in.