The problem was the TKO combo with Kael'thas Sunstrider and Inner Demon where you could do 20dmg for 7 mana, but now that combo is 11 mana so it can't be done in 1 turn. If they want to do that combo now they need to run bad cards like Blur or go to Wild format. The nerf was strictly to disable that TKO.
Well, this is sort of my point. I feel they made it stronger!
Definitely not. Postponing things like Glaivebound Adept and Satryr Overseer one turn is a huge difference. I've had situations, when it was extremely clunky and turn 4 Overseer gets answered much more easily than turn 3. Sure there are scenarios, where you can pinpoint advantages of current iteration of the card, but this only adds to my point - the card is different, not stronger or necessarily weaker.