Level 80 boost service is bugged.

[Holte89]

My mana and health regen, hit rate and expertise is like it was in lvl 6, even though i purchased the 80 boost and are now lvl 80. lvl 70 mobs dodge or miss every blow. Fix this fast please, as i am eager to play my new char.

[3nTRoPy]

On top of the level difference, you still need hit rating, expertise and the appropriate skill level to successfully hit targets. At level 80 the base regen values are extremely low. Try going in some places like under dalaran, and just punch some mobs there (it is important that they are at least level 76 or the level difference will cause you to not gain any weapon skill). Check your skill with the weapon type you are wearing and you will see that it is starting to increase despite the misses. Alternatively you can join a rep farm group in icc and do the same thing there. Fighting level 70 mobs in borean tundra won't work as they are too low level compared to you.