It's an attribute that is picked randomly for both sneakers clashing. It's the most valuable stat that will influence the outcome of a duel.
What else matters? How the winner is chosen?
Besides a master stat which is randomly chosen for each Clash, all other attributes of a sneaker matter: each attribute is weighted by the system and calculated into the total score. Also, the number of steps made weights too and then added to the final score.
The master stat for your duel is randomly set to the 'Balance' attribute. Your sneaker has a 1000 'Balance', and your opponent's sneaker has a 950 'Balance'.
Your sneaker will win if the sum of weighted other attributes, besides the master stat 'Balance', and amount of steps made will score higher than your opponent's.