He's between 6' 5 and 6' 11 and has incredible arm length. He can dribble, pass, shoot and, by having body length, can deflect shots & passes.
Of course there are guards like Westbrook and Mitchell. But there are no Mark Eaton's or John Stockton's or Karl Malones. Rather, teams are built around this ideal NBA type - the versatile small forward.
It is this uniformity of player type that contributes to the uniformity of game style by the typical NBA team.