Few match ended unexpectedly, maybe we would see more unexpected results on the remaining match? like West Ham and Manchester United won. 
We should know that everton and brentford have been a threat for those superior teams which is why they don't defeat them so easily, so for the fact that arsenal was unable to defeat this two teams does not mean that they're incompetent. Of course this two teams have been very consistent with thier performance lately which is why I wasn't surprise to see the scores, and this thier upcoming matches is still going to be a little bit tough for arsenal. Though they might likely win 1 of this matches.