I think the importance of today's Brentford game is high. If Arsenal can win this match, the difference in points will increase. According to the result of the match with Manchester City, it will now be easier to talk about who will be the champion in this league. I don't think there's any reason why Arsenal shouldn't be champions 
Because Arsenal lose in their last game to Everton it doesn't mean they will still lose to Brentford.The reason of their lose to Everton could be because of slight mistake that they might not make this time. I know and very sure that Brentford can not beat Arsenal.