Naw, you are looking at it all wrong. Maybe, those 4 top teams (all finished within 3.5 games) are just really damn good and because of a weighted schedule (assuming you had one) beat the hell outta each other, thereby dragging their records all below .500.
Did I mention how much I hate the lame-ass weighted schedule of MLB? Sucks worse as a Rangers fan. You know how many games run past midnight?
Anyway, I doubt what I proposed is what happened, but it is possible, no?