Is a 359 epic better than a 333 rare? Yes.
Regardless of the specifics in the secondary stats, since you gain more of your primary stats, it is better. What largely defines the difference between druid DPS gear and druid tanking gear is your reforging and gemming. You will actually get Dodge if it's a tanking piece as your reforge since no leather pieces have dodge to begin with. The raw agility and stamina increase though makes it a better tanking piece than a 333 rare regardless. Is it the ideal piece, no. But is it better than a 333, absolutely.
"In anything, if you want to go from just a beginner to a pro, you need a montage." /w TankSpot WTB Montage for Raiders.