You have two major issues
1. Unbuffed spell damage 300
2. Pure avoidance is a little low (48.13 dodge/parry/miss)
You will have to be aware and attempt to take steps to get around them.
At 300 spell damage you will need to use flask of blinding light and spell damage food etc because the locks and mages aoeing stuff is going to drag it off you if you dont. The recommended base is 400 spell damage unbuffed.
Your pure avoidance being low you need to make sure the other tanks peel the abom's off you I dont know if I would like to see you with more than 1.
Final comment it's cheaper to chant for spell damage and get a spell damage shield than it is to gem for it. Everywhere you have the spell damage/stam gems really needs to be the regal nightseye dodge/stam gem and for hyjal. The hands are a free chant slot you can just put a +20 spell damage on it you have a +def atm and you are way way past uncrush like 106%. I carry diff hands one with +threat chant for boss tanking and for hyjal and aoe tanking spell damage on gloves.
** Remember Warcraft players fail in directions you never thought possible.