I have a lot of ideas regarding game balance (this can apply to anything, but real-time strategy is easiest with which to explain). Because a "balanced game" is vague concept.
Does it mean that a beginner would do equally well with every race/character/whatever? That's reasonably easy to accomplish. Maybe it means that if all races are played at their very best then it's a balanced game? That's a more difficult task to achieve, since it's hard to playtest and find out all the little tricks to become the 'perfect' player. (Think in StarCraft, where it wasn't until fairly recently that SK Terran evolved to be the 'best' way to play Terran vs Zerg; or in Super Smash Brothers Melee, where playtesters surely didn't anticipate or test the balance of a SHFFLing laser-spam Falco).
What if one character starts out as easier to beat someone else with, but at higher levels the trend reverses (in SSBM, think Marth v Fox. Marth is easier to pick up, especially with the c-stick, but Fox is ranked higher in the Tier project.) Does that imply that a game in order to be balanced has to be balanced at all skill levels? That is an incredibly more difficult task to accomplish.
But you can't simply dismiss that as impossible to achieve and focus entirely on making the game balanced at the very highest levels. If Protoss loses to Zerg every game before the Protoss hits A-level, the game is still imbalanced since it demands a much steeper learning curve from the Protoss player than the Zerg player. Or is it really?
And what about maps and/or levels? Marth has a tendency to dominate on Fountain of Dreams, while Fox can easily abuse Hyrule Temple. (The difference between the two - and another thought-provoker - is that Fox abusing his level is impossible to stop even at the highest level of play, whereas Marth's advantage can be nullified once both players reach a certain level of skill where it doesn't matter anymore).
Starcraft faces that problem - trying to make maps balanced for all possible matchups (TvZ, ZvP, PvT). Some maps (Luna, Lost Temple, etc.) have come close to balancing all three matchups, but it's freakishly difficult. For example, P requires open space in the middle in order to have a chance to break a Terran push, but open space also makes it much more difficult for a P to defend against Z in midgame. Hence why Mercury was otherwise a fine map but a nightmare to play PvZ on. Leagues have not yet begun adopting maps tailor-made for each matchup (i.e. a map that might be terribly imbalanced PvZ and ZvT but is only used for PvT anyway), but I suspect they will soon enough, however inelegant and awkward that solution may be. Similarly, it seems impossible to me that every map in the SSBM community's map pool is balanced for every character matchup.