The definition of athletic probably needs to be revisited.
Most people would say athletic means how high you can jump, how strong you are, how coordinated you are, how quick you are, how fast you are, and how much endurance you have.
There are a couple other factors that should be added in. One is reaction time. Another is the speed at which you process information (not the same thing). Another factor is build and center of gravity.
I think these should be included in athleticism because they are just as much a part of athletic performance as the other, standard definitions. An "athlete" with poor marks in these abilities is known as a "stiff". People might draft him high on potential, but the reality is he never had potential, he is just tall-strong-fast-whatever.
Look at Jason Kidd. He doesn't change games because of his "athleticism", although he had plenty in his time. He just sees more, and faster, than everyone else.
Look at Nash. Without his incredible reflexes, balance, and "cpu" speed, he would not be a top player. He might not even be an NBA player. Yet these don't show up on standard tests or a decathalon (though he would probably do fine at that too).
I realize most people do not include neurological factors into athleticism, but they are a dominant difference-maker between the stiff and the player, the starter and the star.