I mean, I can understand that Charge lets you go face because I can imagine someone saying "CHARGE!" and attack their foe. I can understand that a Battlecry is an effect that happens when you play a minion because it's like their entrance into the battlefield, cool, but why playing a higher-cost card corrupts anything? Am I missing a WOW reference or something?
Also as a side note: this corruption seems to be similar to what they were doing in the Whispers of the Old Gods expansion. But, instead of having two separate cards (normal and corrupted), they are now one card that powers-up into its corrupted state when played late.
Corrupt is a new keyword a card will have --- like Battlecry or Deathrattle. Only those cards can be corrupted. Y'Shaarj is not one of those cards; Y'Shaarj adds other cards you corrupted and played back to your hand.
But for the theory of a 10 Mana Corrupt card releasing, you'd probably have to play a card to reduce its cost, like Skull of Gul'dan, and then play another 10 Mana card, like Faceless Behemoth.