He pretty much fits the pro hockey definition of "loser":
A huge talent, picked 1st in the OHL draft, 2nd round to NHL. But is lazy / stupid / scared / heartless and never develops properly. Now his NHL career is pretty much done and he's a career minor leaguer despite tons of talent. I bet a lot of hard-working AHLers look at O'Sullivan and wish they had his talents, and wouldn't squander it.