Perhaps your equipment is not up to the task (at the moment you will most likely also be placed against very developped accounts) or you are banning the wrong champ of the opponent. 

Expect your opponent to have at least 350+ speed with Speed boosters or 300+ speed without them....

This will change in a few weeks when everybody has spread out among the Tiers

Check the opponents level. If it's easier a lot higher than yours, ie, Lvl 100, expected to get thrashed - unless you are also lvl 100. :)

But when fighting opponents of similar level it comes down to drafting and banning, and having a decent team left over.