Serious question. What was wrong with elise before?

She was overnerffed.

To be fair to Riot though: Elise has generally had the same meta viability as Ryze and Kassadin. 100% pick/ban and at the top, or 40% win-rates and on the bottom.

she was too weak if you built her dmg or she had no dmg if you build her tank. also kind of useless late game

The problems with Elise had to do with her unpopularity. She didn't have many players interested in playing her because she was overnerfed. Her problem is not 100% pick/ban vs 40% win rate and on the bottom though. That was not the case at the time she was overnerfed and it isn't the case in the recent buff either. Also to be clear, almost all her recent changes have been neither buffs or nerfs and this is why RIOT has had such a hard time with Elise recently. It took RIOT a long time to admit that Elise needed some power back. As I've said elsewhere, now that she has been buffed she is actually in a good place right now. The ban rate issue is player base overreaction because players remember the Elise of old (which Elise has not been returned to).

She's cancer.