I had a Defender Pig. I named him Shadow, and I wuvved him so. The pet expansion came, and I wuvved him more, giving him food and playing games to try to upgrade him.
I upgraded him, and now he's worthless. He's worse than worthless. The new talent makes him give out a Sacrifice Minion card. I don't use minions. I definitely don't sacrifice minions. My deck now has poison in it, a worthless card that could be drawn instead of a vital card in a time of need. My pet can now get me killed.
I want him back the way he was. I'll settle for only having him as an adult and progressing no further, because at least as an adult he was very useful to me. I'd even pay gold for the dubious privilege of reverting a pet back to a younger state, because I can't use him as he is now!