I don't think Blizzard wanted to nerf Undertaker, but I also think they had no choice.

The Undertaker nerf solves the "1 turn win" problem where if you didn't draw (and use) a nuke on Undertaker the turn he reaches the table he'll snowball out of control.

Yes, eventually you could kill him by sacrificing 3 or 4 cards for it but now you lost board control and 15+ health points. If you were fighting an agressive deck like Hunter he could just hero power you down from this point foward.

However, now Undertaker is out this means slower decks have less things to worry. The meta will change and other balance issues may arise. Yes, Undertaker losses were annoying, almost worth a instant concede BUT the players to deal with early game agression

The 10% bullshit loss may be gone, but I feel some specific  decks will win now with with far more consistence because they can ignore the early game since there is nothing there to contest them.

Whatever, I have a Dr. Skill now anyway.