Is there a fine line between racism and honest commentary?

Yes, that is racist. You're saying that because of skin color black people are inherently more skilled. You're forgetting that players put in hundreds upon thousands of hours of practice to hone these skills. The fact that there are more talented black basketball players is only a fact because as a whole, more black people than Eskimo's play basketball. It's because there are more of them playing, and as such, more of a chance of talented players.