Well, yes and no. If his lower quality guys are playing at the best of their ability, they can beat stronger teams. In general, the quality difference of one star doesn't seem to be much, I have lost to weaker teams when I put out a formation that was a bad counter to theirs, and when key players had bad games.. For him to do so well, he must just get the best out of what he has. Do his players get better ratings than the opponents'? I expect they do for his record to be so good.