It's because, given the way these people are using the word "athletic," athleticism isn't measured on the court. It's measured in units like inches and seconds. For you, it seems more like "good athlete" simply means good basketball player. In that case, he's not a good athlete trivially because he's not a good basketball player, right?
no. good bbll player isn't the same as good athlete, despite probable positive correlations. almeida for example, i think is a good bball player, but i do not consider him a very good athlete. in the opposite direction, pattillo was a great athlete, but a mediocre bball player.
i do argue that displayed athleticism over a year and half of playing bball is a better measure of bball athleticism than how high you can jump off one foot after running in from the three point line on an empty court.