Sion should be on the radar for patch 8.5
Unless if the darius buffs will give him an actual statistical challenge, Sion is going to continue being the absolute #1 top laner.
http://www.op.gg/champion/sion/statistics/top
His play rate is now a healthy 8.6% while maintaining an asinine 55+% win rate. His statistically WORST matchup out of the entire top lane roster is yasuo, WITH WHOM SION WINS OVER 51.5% OF GAMES.
The 8.3 bugfixes were massive, it's time to realize that now that these bugs are fixed, some of the numerical buffs sion has received over time should probably be scaled back.
No, the new rune system is NOT the problem, before patch 8.3 sion had a normalized win rate and relatively low play rate. Any arguments stemming from the rune system will be curtly dismissed as sion would have become the apex predator at the start of the preseason rather than several patches in.
And so with that said, let it be known that sion is objectively broken and healthy. That is, Sion is a champion whose kit is fine, but whose numbers as they stand are simply overtuned as of now.