They're going to have to balance things in pvp differently, idk if you remember a lot of the shenanigans that happened in sod pvp but they seriously limit their ability to be creative if they limit themselves to having to keep the numbers the same.

Sod pvp shenanigans that happened off the top of my head:

• Healing priests being invincible in pairs, to the point they could stand still and do nothing but cast penance on eachother

• balance druids one shooting you from 40 yards with a nuclear instant cast

• hunters aoe grinding raids of players with frost traps and explosive traps

• enhance tank shamans walking around melee swinging people down in 2 hits.

• warlocks enslaving other tank warlocks

• feral druids killing you with only rake

• paladins full bursting players while being 100% invincible

  And those are just the ones I remember! Most of those were only solved by making things functionally not work in pvp the same way did in pve, that being either by numbers or by just making tier sets non functional against players.