Tell me the "many ways" Shaman deals with pyro, please! Cuz I'll leave this thread, go play and never return!
Shaman is the weakest class against mages. If you're trying to use Shaman as evidence that mage is overpowered, that's a poor argument as it is the worst class to try and beat a mage with. Like most card games, the game is a big rock-paper-scissors, and as such, not all 1v1 matchups are equal. What makes a class imbalanced is when they're the rock in rock vs. paper in almost all potential matchups; no class is currently like that (trust me, I've actually seen classes in the earlier stages of the game that were).
Plus, it takes no skill to LOSE a game. Anyone can lose a game. If losing proved that a class was too strong or weak, then I could prove that any class was underpowered by conceding 100 games with it. If you want to show that the mage class is overpowered, then make a mage deck yourself and become legendary rank in the first week; if the class is as overpowered as you say, it will be an easy task.
I'll tell you the truth though; you will find it isn't. But beyond that, you'll learn a lot about playing against the class by playing as the class, and it will actually be quite good for your player progression to do so.