No, combat advantage means that the enemy is on the back foot. It can be interpreted in a great variety of ways, common ones being catching the enemy by surprise of flanking him. In your case, you use your talents for subterfuge and sleight of hand to confuse the enemy as to where your attacks will be coming from, causing him to leave holes in his guard.

There isn't a mechanic for aggro (well, there might be some exception, I think there was a spell in 3rd edition that did that), I pretty much determine who gets attacked based on how I imagine the characters in question would act.