I'm missing uniformity in the reasoning behind buffs and nerfs.

On the one hand Riot presents us:

Turrets

All Turrets base health decreased.

Game length has gone up with the addition of this new turret, but it's a little higher than what we're happy with. We're going to quote the designer on >this other context: "The nexus turret however, remains unchanged - a last bastion of hope braces against the inevitability of Winter eternal."

How eloquent.

OUTER TURRETS 1850 health ⇒ 1650 health INNER TURRETS 2050 health ⇒ 1850 health INHIBITOR TURRETS 2350 health ⇒ 2250 health

But on the other hand we have:

-Nerfs to Righteous Glory -AP Items that scale harder into late and do less damage early -The return of farm junglers thanks to devourer

Looks pretty arbitrary to me.