Y'Shaarj requires you to both corrupt and play the cards, in order to get them back for 0 mana. Which, in the case of most all Corrupt cards outside Strongman, can be both difficult and extremely time consuming. In my experience, he only comes down in the late game or right before fatigue hits for Druid/Warlock, when playing against other very greedy decks.
Basically, he's a non-factor or a really bad draw against decks that plan to win before the decks empty out. So I think he's fine.