Getting the same exact ring the following week. Womp womp.
I just had my rings crafted and bought/upgraded the rest of my PvP gear.
No RNG necessary.
I get bracers if I only have one slot. I get trinkets if I have more than 1. I could actually use that 616 ring, especially if it dropped with a socket. 
Maybe thats whys theres 3 slots
To be clear this was from Timewalking.
id recommend switching to a different spec before claiming your vault. it will give another chance at something else.
I only play blood but people want me to play dps (so i assume frost and frost uses 1handers) so when its my weekly vault claim, i switch to frost - claim and 1 time in the last 2 months I got a 616 1hander weapon, still waiting on that 2nd one hahaha
Update: I have opened 5 616 bags from the weekly 5 TW Dungeon Quests. I have gotten this 3 times out of 5:
Writhing Ringworm - Item - World of Warcraft