Arsenal knew they would win because Brentford are not playing well, they will struggle this season. Arteta knew it would be easy 3 points which would take them back to the top of the table. I think Arsenal will behind Manchester City, Tottenham Hotspur and Manchester United and they will be challenging Liverpool for the 4th and final Champions League spot.
Arsenal will not be able to maintain their form, they will probably fade away out of the top 3 by the time 12 games have been played.
Arsenal destroyed Brentford which was not a thing I was expecting to see in this game. Because Brentford haven't been having any problem with finding goals recently. Their performance against Manchester United was incredible and I even thought of a possible upset for Arsenal also. But Arsenal got a very reassuring win by 3-0. Vieira's goal from a far distance was really worth watching. Gabriel Jesus continued from where he left by scoring a goal after a break in the Manchester United game.
Arsenal are very determined this season. They aren't intending to leave even a single point against this kind of teams. As long as they continue to be consistent in the games against weaker teams it would be easier for them to make up for their mistakes in the big games. But for winning the title they need to play better against big teams also. The next test is against Tottenham in Emirates. There are two weeks for the game and it's quite enough for them to be well-prepared.