Did you not learn from Warwick?

Mystic Shot (Q) AP ratio increased to .5 from .4 Trueshot Barrage ( R) AP ratio lowered to .6 from .9

So AP ezreal is getting nerfed, because Runeglaive is a stupidly niche item which removes almost every weakness in AP ezreal. Not only that, but it looks like Runeglaive is also getting a nerf, with the wording sounding like the AOE only applies on monsters.

In fact, what is so stupid is you are buffing the part of his kit which is most of the problem at the moment with runeglaive, and nerfing the part of his kit which is massively telegraphed, easy to avoid and has been considered balanced for ages.

NOT ONLY THAT, but runeglaive now doesn't convert the attack into magic damage, meaning Ezreal's Q's now won't benefit from magic penetration. This pretty much counteracts the .1 bonus scaling they added onto his Q, probably nerfing it some more.

Congratulations, AP Ezreal now pretty much depends on Runeglaive in order to be effective. You have simply removed the power from his non runeglaiving kit, and pumped it into the part of the kit that uses runeglaive.

Edit: Obviously I posted this before they pulled the Ezreal PBE changes, we did it..uh.. boards.