I thought it was interesting watching our game on that score yesterday. We were much more aggressive defending set pieces, like the penny had dropped that the opposition were getting away with physical stuff that ought to be given as a foul, so give it back. I think that's the way to stop Arsenal from corners and free kicks. Get your retaliation in first. Aside from anything else, if you engage the opposition in a bit of fisticuffs before the ball is kicked, it usually ends up in the ref blowing up for a foul and nullifies the threat.