Sona got nerfed for having high winrate
http://www.leagueofgraphs.com/champions/stats/support/diamond/by-winrate
how come Blitz is not nerfed while having 55% since one month already?
where are the Leona nerfs?
17.5% pickrate, 53.2% winrate, picked in LCS, LCK and LPL
where are the Blitz nerfs?
21.8% pickrate, 55.0% winrate, picked in LCS and LCK, not sure about LPL
mind you, this is "NOT a QQ RITO NERF BLITZ AND LEONA PLOX" topic.
this is a "why the hell did you nerf Sona for having an high winrate while there are countless champs who have insanely high winrate while having high pickrate as well, as well as being picked in competitive while Sona was picked an handful of times" topic.
Sona just sucks right now, she was perfectly fine after the rework (read: before the 2 nerfs in a row that made her a Q-bot), and you can clearly see this with competitive picks (not picked not only in LCS, but also in LCK and LPL).
I'd argue that Zyra sucks too since she has yet to be picked since last summer but that's another story.