When the riding is so close, the smallest of details can separate one rider from another. Doing an extra 180 more than the guy before you no longer matters. What comes into play are elements like grabs (and legit ones, at that), amplitude, creativity, variety and execution. There are even details within those details. Take, for example, a crow 5. All of the top riders on the PWT do them, and they are a staple in the finals, but not all crow 5s are equal. A nose grab crow 5 is easier than a mute grab version (and the same can be said for a back mobe 5), so you might see a rider with the mute one get a little bump in the score. If two guys both have grabbed toe 9s, what separates them will be how well the trick is grabbed and how long it's held (yes, the judges can tell).