Center depth isn't what is plaguing Toronto. Their top guys are putting up numbers, but they can't keep the puck out of their own net. Whether is be a goaltending issue or just piss poor defense, the forward group is not what is maligning them. Marner (12), Matthews (11), Rielly (11), ROR (9), Nylander (8), Tavares (7).
Their top 5 forwards are carrying the load and doing it well (along with their #1 D). It is the rest of the roster that is letting them down. Trading one of their top guys up front is likely, but it won't be for just another top 6 forward. Would have to actually address their needs on defense.