Generally speaking, if you say someone “knows” a sport, you are saying he has a lot of experience with the sport, has developed instincts that are useful in the sport, understands the nuances of the sport, and possibly even knows the history of the sport.
In that particular ad campaign, I think the use of “knows” was ironic. He excelled in the sports he played because was athletically gifted (and wore the appropriate Nike sportswear, the advertisers are suggesting.) And because of that ad campaign, “knows a sport” gained a new meaning, among the generation that saw the ad. That new meaning was “is very good at”.