Do not focus on avoidance, try and name one boss other than Saurfang where avoidance is favored compared to EH. Here is a rough list of bosses that have been killing tanks in current content:
Algalon: Bursts down a tank so quick that if you stack avoidance you will get insta-gimped.
Gormok: Kills the tank with a melee, Impale, Bleed combo, Impale and the Impale and the Bleed are unavoidable so the only thing that you can prevent from hitting you is the melee so if you don't have enough EH to survive the combo when that melee hits which it will eventually you will die.
Marrowgar: You die from getting hit 3 times in a row without heals for what every reason. If you stack avoidance here you rely on RNG too much and when that 3 hits happen which it will eventually you will die so you might as well give your healers a bigger buffer.
Enchant all of your gear with EH and gem all 30 stamina unless the socket bonus is 9 stamina or higher.