Well balanced in street fighter terms comes down to the saturation of tiers, and how diverse top level play can be. Every fighting game has a high tier, no matter how well balanced they try to make it. The interesting part is how tiers evolve over the lifetime of a game. New tactics are discovered, strengths and weaknesses shift and the game moves on.

There are a lot of factors that come into tournament play beyond inherent tiers. Matchup experience, fatigue, ego, execution percentage, mind games. It's a far more interesting world than it may seem at first glance.