Can we get some information on the PBE range changes to several melee champions?

Don't get me wrong, i believe this is a great idea. I'm just wondering if those buffs are actually buffs or just compensation for some hitbox calculation formula.

For anyone who hasn't seen this:

Source: http://www.surrenderat20.net/2015/11/1110-pbe-update.html

Gnar Mega Gnar attack range increased to 175 from 150

Nasus Attack range increased to 175 from 125

Nautilus Attack range increased to 225 from 175

Sejuani Attack range increased to 175 from 125

Sion Attack range increased to 175 from 150

Shyvana Dragon Form attack range increased to 175 from 125

Tahm Kench Attack Range lowered to 175 from 200

Trundle Attack range increased to 175 from 125

Xin Zhao Attack range increased to 225 from 175

Zac Attack range increased to 175 from 125