I would prep 6.15 Ryze nerfs because he will be too strong in 6.14 and wouldn't consider win rate as a factor whether it is good or bad on the initial release (I know historically Riot loves preemptively buffing Ryze before giving him time to gel which makes him insanely overpowered, also nerfing certain star dragons).
Since Ryze is suppose to be a hyper mage it would be early game power you shave off so that he is at least balanced that way:
Damage changed to 50/70/90/110/130/150 from 60/85/110/135/160/185; bonus mana ratio to 3.5/4/4.5/5/5.5/6% from 3%
**Spell Flux (E):**
Enhanced root duration reduce to 60/70/80/90/100% increased duration from 100% (2 seconds root at levels 2-3 is a little oppressive); root duration would end up being 1.6/1.7/1.8/1.9/2 seconds from 2 seconds
**I forgot what this is called (R):**
Cooldown to 160/120 from 120 seconds (or 180/120 or 170/120 seconds)
Range increased to 3000 from 1500/3000 units (feel like this a little too short for rank 1 value; would rather see it up less often with a longer range this also allows Ryze's opponent a greater window early game to take advantage while his ultimate is down)