As i have no access on the us forums to post , i will create a replica here. For those who want to read more please check the original US post here:
https://forums.worldofwarcraft.com/thread.html?topicId=27397548532&sid=1&pageNo=1

Short version : "Concerns about lack of magic reduction cool down for warriors to match Small DR: Barkskin - Divine protection - Bone shield "
It was suggested to make Shield block 20% flat damage reduction , a glyph that will morph Shield block and so on.

A more elegant solution to the problem is to let warriors use Spell reflect for both PvE and PvP.

Just create a glyph ( major as this is not something that enhances our abilities without a downside. ) :

Glyph of magic shield or whatever name you like: Your spell reflect has a 10 second duration, magical damage reduced by 20%, no spells will be reflected to the attacker and the cooldown is increased to 1 min. Using the Spell reflect will cause cooldown on your Shield Block.

I hope Blues read EU forums also.