I've found that judging the team by average quality is a very dangerous thing to do...I've come across several teams where the ave. quality is much lower than mine, but only because the subs are poor.
The first team was actually superior to my team, meaning I should have played different tactics...that was why I lost, I guess.

You do get some 'troll' results, but when you see a pattern, you start realising why and it's almost always tactics/formation. Sometimes an especially poor performance from an individual can cause this, also.
I've found there may be 1 result a season that is inexplicable and it's almost always a game that doesn't matter in the grand scheme of the season.