Questions about new pbe updates on Ryze.

Overload (Q) damage changed to 60/95/130/165/200 from 65/95/125/155/185 Overload (Q) mana cost changed to 40 at all rank from 30/35/40/45/50 Overload (Q) new effect "Arcane Mastery's cooldown reducing effect is increased to 105/110/115/120/125% of Overload's cooldown"

Rune Prison (W) cooldown increased to 24 seconds from 14 seconds. Rune Prison (W) root duration changed to 1.25 seconds at all ranks from .75/1/1.25/1.5/1.75 Spell Flux (E) cooldown reduced to 7.25/6.75/6.25/5.75/5.25 from 7 at all ranks Spell Flux (E) mana cost reduced to 60/65/70/75/80 from 60/70/80/90/100 Spell Flux (E) damage lowered to 16/22/28/34/40 from 25/33/41/49/57 Desperate Power (R) duration lowered to 4 seconds at all ranks from 6 seconds.

They are lowering his cds for overload and spell flux. Even with his cd reduction ult and passive those are really short cds. But why do they reduce the mana cost also? isn't that counter intuitive? He stacks mana for damage and his cds would allow him to dish out alot of spells so for counterplay he has to watch how much he spends. So why is it balance to reduce the mana cost?

I'm just curious, please don't kill me. :(