Berlocq is probably the best example currently.
Soeda doesn't even fit this definition to me, because almost all of his good results in challengers are in weak challengers in Asia or poor entry lists in HC challengers when most guys are at better events. He's basically played the system to get where he is, and he'll probably be out of the top 100 after next week.
There you have it. He fits the definition perfectly. He is good enough to get inside the Top100 for a little while but then immediately slips down the rankings simply because he can't retain that spot.
That's the barrier right there between a Challenger player and a Tour guy.
Chardy is going to play some challengers soon, that doesn't mean he's not good enough to jump back into the Top50.
That's the difference, Soeda will never get passed that nr.90 in the world even if his life depending on it.