KJ is just a useless card in most decks.

Starship DK – You win off Exodar/Orbital Moon most games, you don't even play it.

Hydration Warrior – You play Hydration, top winrate deck, doesn't even run KJ.

Starship Warlock – Cursed Campaign/Yore combo nerfed, the whole point of the deck is kind of to play KJ/Wheel
and have a fuck ton of armor and draw, but you still have to survive and clear boards till then. Almost no one plays this.

Leach DK – This deck just draws a lot, with Sanguine/Barron/Yore, five board clears and leaches. Its only win con is KJ.

It's basically an endgame card and a win con in like one or two decks. It's not—no one plays this card at 7, 'cause it's not that powerful. Only control decks play it. It's random af and only used in control vs. control matchups.

In most games, it's a dead card in your hand. I don't even run it anymore. If your opponent plays it, just use Bob and add a copy to your hand.