Actually DKs are very very solid MTs! I have seen some logs of DKs with 80% avoidance on boss mobs. Thats pushing ridiculous levels of avoidance.

edit: The more I read that quote the more I think they removed Blood Aura from affecting your group/raid which pretty much guarantees that it will no longer stack. This also means that all DK groups are pretty much done PvE wise. I look forward to being proved wrong though!

editx2: Read this thread if you are interested in how OP DK tanks are =)