The stats in my example are real life stats. I can only run a certain speed and lift a certain rate. However, I'm not garunteed to be punched repeatedly in the face without being able to block it because my opponent is faster. Of course getting a faster opponent would logically make it now difficult but not in any way set in stone. Not using stats as run speed would allow me to claim I can actually run faster then what I had originally had in mind, so it would indeed have more freedom that way but you still have tons of freedom even stating their max run speed.