Post a link to your armory (if you're currently saved in other gear, link to your Wow-Heroes page so we can see the tank gear you were previously saved in), and tell us what kind of content you're doing.
Since you're still worried about defense, I assume you're a relatively fresh 80, in which case avoidance is still something to keep in mind. Your current levels of avoidance are pretty high (higher than my Paladin), so I wouldn't worry about it anymore and you could certainly trade out some avoidance for more EH (stam or armor). Block is nice for tanking adds or heroics, but except for a few gimmick fights, is nothing a raider should be concerned with. For a raiding tank, block rating is useless and block value is a pure threat stat (a pretty nice one though).
Again, an armory link would help us with determining the root of your aggro problems. Are you using the cookie cutter 53/18 Crusade spec? Are you using the Seal of Vengeance glyph?