Westbrook had a very pedestrian 36.5'' max vertical coming into the NBA, but he is probably the most explosive player in the NBA. James Young has a 35.5'' vertical, but he is not nearly as explosive of an athlete.
I think what sets Westbrook and Brown apart is the quickness with which they can leave the floor in a variety of different ways (both feet, multiple directions, two foot, etc.). Neither guy needs a completely clear lane to do it either. They can handle a little contact on their way.
Not saying Brown has Westbrook's level of athleticism, but I do think he has that kind.