This guy explains it well:
Look, Manu [Ginobili] isn't Jordan. He's not Kobe. He's not LeBron. Rooting for guys like that is unimaginative and frankly, boring. They won the genetic lottery. They're bigger, stronger, faster. Wheee. Root for them and you might as well root for McDonalds and Nike (shockingly companies those guys endorse or have endorsed). You might as well cheer for Team USA in the Olympics against Team Argentina. I have no use at all for people like that.
Manu isn't your favorite player because he's perfect.
He's your favorite because he's not.
He's Rocky. He gets knocked down. He loses. He fails. He occasionally does really stupid shit in really important games.
But he cares. You can see every second he really fucking cares. Even in the regular season when 99% of people affiliated with the NBA, including the fans, don't care, he does.
And that's that.