where are you getting 27 from?
Ljubicic, Soderling, Ferrer, Verdasco...all that players start to play really well with 27 or so.
He has just lack of self-confidence and one day he will have, because he has potential. He just needs to keep fighting what he does. And he will be mature with 27.
He is just too good to not become regular top 10 player one day. But that day will not be in next 3 years. Just after that.