the premiership

It's not fixed. In England small teams have a goal: Beat big teams, i mean they realize that they cannot win the league, so they put all the effort to win when they play against big clubs. Although the big teams may have a little bit too much confidence before a match against a small club.

Every sportsman have their day dude. No one is invincible. Fixing games never came to my thoughts when one of those big clubs loses to smaller and lesser known clubs. One thing for sure is, is the big teams usually have too much confidence and they also rest a lot of good players while playing with smaller clubs. So, the chemistry might not be well with the playing players of the bigger clubs.

It certainly is not fixed. Every team has their bad day and when you combine a bad day with a smaller team being up for it then you can easily get these kind of results.