Shadowban on low gear bracket BG queue

Hello

I have pretty good understanding on how the low gear bracket BG queue works gear wise
Problem is that out of the blue (without upgrading any item) my sub 4k GS char is no longer able to be placed into the low bracket
Tried for the last week at various times after deleting some high ilvl gear and even went as low as 3k GS
I can go back to low bracket on my alts after deleting the item that overshot me with no issues, getting into low bracket consistently

So the question is:
Is there a system in place that automatically puts me to upper bracket after (lets say) certain amount of honor gained or HKs achieved?
Anyone experienced something similar?

I assume you got a new item. If the item is currently not available on Frostmourne it'll put you in higher bracket.

Thats kinda the problem here - I did not change any item for some time
After I went over the gear cap, I deleted the last item and enjoyed consistent low bracket

For the reference - char with the shadowban:
http://armory.warmane.com/character/...ecrown/summary

And a char that works - consistent low bracket:
http://armory.warmane.com/character/...ecrown/summary

My only theory right now is that my mage is shadowbanned (or whichever term you want to use) for playing too much low bracket and not upgrading gear
Especially when you compare the gear - no other gear in mail, AH, bank or inventory of course
I went over the cap on my shaman too then reverted to a gear state that worked and works to this moment with just less BGs played, honor gained and HKs achieved

EDIT: I can now join low bracket on my mage - fixed by divine intervention I guess