In my (limited) experience, league matches in the first week are a COMPLETE crap shoot; the results seem almost entirely luck-based. As the seasons go on though, the good teams start winning and the bad teams start losing and by the end of the season the table should look like it is meant to.

I have speculated on my own that this might be deliberately part of the game to try and motivate managers of lesser clubs to not give up hope. Personally, I would feel the shame in getting destroyed by somebody who is trying would be motivation enough, but I cannot think of any other reason why these early league matches are such coin tosses.