'average' is a very personal concept. Everyone here is average on bnet, as the system is intended to have you play at 50% with some ups and downs for its miscalculations.
My ex-gf said she was a good at ski'ing as she could do black. But she sucks, at it took her 50 minutes to get down 100 meter. The same here: what is average? it is to hard to define.
If you play RT and never solo, you are probably far below average though, as low-mid solo are often better than top RT.