From my experience, Quality and Formation and Order are the most important factors. I rarely do bad against lower quality teams, but the margin needs to be high. Less than 20% in the quality difference isn't really that noticeable.

Then comes the formation. I don't hesitate to change my formation in games if I see my possession too low, and regularly I see a pretty noticeable change when I do so -- either it drops even lower or climbs suddenly. There's also some logic to it, but not always very intuitive.

Then comes the orders. The orders with which I have seen a clear impact in games, are the Mentality and Pass orientation ones. I haven't noticed any noticeable game change with the others -- but that's probably because I don't change them very often.