It took all of 18 seconds for QPR's defence to go into meltdown mode. With Mikel Arteta in possession, Clint Hill led a mad charge towards the ball, and that opened up a gap for the Gunners captain to slip a pass to Theo Walcott. Robert Green couldn't get enough on the subsequent shot, and it was 1-0 Arsenal.
That was all the visitors needed, and they knew it. I mean, sure, Walcott had a couple of chances to add to the lead, but the 18 seconds it took for him to score constituted the only part of the match that was even remotely compelling. Yeah, Arsenal didn't look good, but they were playing against QPR in a game that they'd pretty much won in the first minute. With the hosts incapable of mounting a real attack*, it's no wonder that the Gunners were content to have the ball.
*Andros Townsend was quite good, though.
It was always obvious that Arsenal had several more gears they could have gone into to secure the points. But the simple fact is that they didn't need to. That made the game pretty unwatchable, but Arsene Wenger has bigger fish to fry than ensuring that his side is entertaining.