Gunners in fine form and Dutchman leads the way with his 29th goal in this calendar year and two assists as Baggies are easily dispatched in North London
Thomas Vermaelen and Mikel Arteta were the beneficiaries from their captain's creative display, though a fine performance from Carl Jenkinson at right back did not go unnoticed.
The home side started brightly, dominating possession as is customary at the Emirates.
A real buzz came over the crowd whenever Robin van Persie came into contact with the ball, but the home side failed to trouble Ben Foster in the opening stages, Andre Santos hitting over from a free-kick with the only effort of the first 10 minutes.West Brom were momentarily down to 10 men as Jonas Olsson went off to receive treatment for a facial injury after colliding with Thomas Vermaelen, but the defence held strong with Steven Reid dropping into centre back until Olsson was ready to resume.
While the Baggies weren't troubling Arsenal in terms of possession statistics, they were threatening on the counter attack, with Wojciech Szczesny diving down to his right to stop a cross while Simon Cox was lurking with intent.
But in the 23rd minute, Arsenal were rewarded for their calm build-up play, as Mikel Arteta beautifully sliced open the West Brom defence to find Theo Walcott.
The winger tried to slot through Ben Foster's legs, but his attempt was stopped, only for Robin van Persie to tap in for his 11th goal of the Premier League season, and his 29th of the calendar year.
That goal served to buoy both the Arsenal team and the fans, with Carl Jenkinson putting in some dangerous crosses down the right wing, and generally impressing.
And five minutes before half-time, the Gunners doubled their lead. West Brom failed to clear their lines after a corner, and Alex Song drifted a cross over to the back post where Van Persie was waiting to cut the ball back across goal for Thomas Vermaelen to apply the finish.
It was a very simple goal for the Gunners, and one that would no doubt have Roy Hodgson fuming in the away dressing room as the visitors headed in at half-time two goals down.
And the manager wouldn't have felt any better about his defence three minutes after the break as they allowed Vermaelen an unmarked header at goal, though they were allowed a reprieve as the Belgian headed wide of the mark when he really should have scored.
It looked to be becoming a case of how many Arsenal would score rather what the result would be, however.
After Chris Brunt missed the Baggies' best chance of the game, volleying well over from the edge of the box, Arsenal almost made it three as Gervinho found Aaron Ramsey in the box before the Welshman turned and dragged a shot just wide of the post.
The game was well and truly put to bed after a double-change from Arsenal, and Tomas Rosicky played a key part, finding Van Persie in the box, who's lay-off was perfect for Mikel Arteta to sweep a shot into the corner.
West Brom did cause some trouble as Somen Tchoyi came on and had a shot blocked with a sliding tackle from Vermaelen, but the striker really should have done better, as Vermaelen was already on the floor when his shot was struck.
The rest of the match fizzled out with Szczesny occasionally called upon to make a stop, but rarely troubled as the Gunners sealed another win.
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