People seem to not know this so.. there you go.
Taliyah was (hotfix) buffed after release too, then nerfed like 2 or 3 times because she was op when people figured her out
https://i.gyazo.com/1a45248014ad2e3f91927dc8127141e5.png plus Ornns win rate is already 42-43% and rising today anyway.
That was not always the case. There's no way for Riot to perfectly balance a new champ because not enough people have played them. New champions used to have really high winrates, which frustrates people even more, because they are new, and they are everywhere, and people don't know how to deal with it. So Riot chooses another way: make them weak and buff them in hotfixes.
it's not perfect, but it's better than the alternative.
Taliyah's actually a difficult champion, though.
Ornn is not. Ornn is laughably easy.
so bad at release
New champions will never be balanced at release because to determine the right balancing approach you need results from thousands of games across all skill levels, low elo, high elo, in between to test new builds and team comps, and the PBE tester base ain't that large
Make Ornn's Q pillar come up faster and there you go; now he's no longer shit in lane.
Except taliyah was shit shit couldnt evne do her W>e OR IS it E>W i dont know which ability is which
Only bit on Ornn is that weak item selection. Should indulge a bit more variety.
Its due to many not understanding anysht to this game. I saw many Ornn building sht items like 
[zombie-brand-mindblown].
This new champ is totaly "basic" there nothing to understand, a classic tank (most of them don't recquire much any skill).
He's honestly a very decent support. His dash's knock-up has a fairly large radius so his Q makes for a very solid zoning tool. I'd rather just wait until his winrate stabilizes over the next month before even considering a buff.
To be fair, I do think Ornn needs a little something to help him out. Namely some kind of fix to his Ultimate's hitbox on the headbutt. It just doesn't work right half the time from my experience with and against it.
