'Sunwell Radiance' is a buff that reduces your enemy's chance to dodge by 20% and increases hit by 5%. Apparently, Blizzard has implemented every mob in Sunwell Plataeu to have this buff. So, if you have been a tank and noticed your dodge drop from 50-60%~ to 30-40%~, this is indeed an intended change. Blizzard may have put this change in to compensate for the amount of dodge/avoidance that was given on T6 gear and also keep under geared guilds out of Sunwell Plateau a bit longer.
There has also been confirmed reports via WWS(WoW Web Stats) that tanks are consistently dodging 20% less than before.
A statement on wowhead.com from a frustrated tank
"I noticed this gimmick on the very first pull in sunwell. I can tell you that this is a game breaking change for all sunwell tanks. Why couldn't Blizz design a working tanking mechanic instead of grossly patching our horrible itemization with a nerf like that. Sunwell Radiance basicly cut 25% of our avoidance. That is the equivalent of retrograding a T6 tank to pre-kara level.
The only benefit from it that I see is the reduction of rage starvation from extreme level of avoidance. But how do you expect our healers to react to this? They are used to heal 55%~60% avoidance tanks and now have to deal with a 30%~35% avoidance tanks. This change is unacceptable to me. To counter this, we now have to wear insane amount of avoidance. Gear setup that is rediculously useless outside of Sunwell."
Source: WoWHead.com, WoW Forums EU
WoW - Former Guilds / Teams
-Captain of x6.WoW (Check-Six) during WSVG
-Played for Fnatic.WoW with Insurrection
-Co-Founder of the Eminence Guild on Blackrock
-Formerly Trance of Tichondrius
-Current Guild: Vicious Cycle of Blackrock
-Founded CAL-M and CAL-I team |e| (Team Element)
-Founded CAL-IM team V7 (Violent 7)
-Went under the nick 'sHadEz' in CS
-Former member of team W.E.W. (Weekend Warriors)
Starcraft / Starcraft: Brood Wars
-Founded the Guild [e]lement on USEast
-[e]lement held a 70-21 record in unofficial guild matches on battle.net
-Team [e]lement was the original guild of team USA players 'Saddles', 'Nooks', 'Tempest', and 'Nony'.
- went under the nick 'shad[e]z' or 'shadow[e]'
SK Gaming at the European WoW Regionals
Joefernandes Leads New SK WoW Team
World champion Joefernandes talks BlizzCon
SK Gaming chats with Sid 'Supatease' Compston
SK Gaming is the 2015 BlizzCon WoW Champions
THE NEW JERSEY