Isn't the problem that fundamentally they are "good" players but not a "team". Happens loads in football.
That is the top and bottom of it; looking at all of the signings that were made since the summer transfer window opened, I wouldn't say any of them are bad players, in fact I'd rate most of them as good players, they just happen to make a lousy team. I think a lot of the issues stem from Melville/JED running amok like a child in a sweetshop when the Chinese money became available, signing every decent player that became available without looking at how they'd fit into the overall team or even if they played in a position that we needed extra competition for.