There's a difference between elite player and "superstar", at least to me.
A "superstar" needs to be an elite player (so players known for stupid **** off the court like Lamar Odom/Kris Humphries marrying a Kardashian don't count), but an elite player doesn't need to be a superstar (it's essentially their choice for how relevant they want to be). I'd expect everyone in the country to know who LeBron James is, regardless of if they even own a computer. Other players I'd think of for this would be Kobe Bryant, Shaq, Michael Jordan, Allen Iverson, etc. Tim Duncan? Maybe, but I doubt it.
To me, a "superstar" needs to have a cultural imprint outside of simply being an elite basketball player.