The AI can't currently handle losing a marked player. If you get ahead of someone who is supposed to be marking you, you can just go like the wind and unless your teammates drag their markers into your path, you will be stopped no sooner than the edge of the penalty box, if at all.
Indeed. I scored this shortly after my most recent post. Granted, I'm using Barcelona against Deportivo Alaves, but watch as no one comes to close me down! I only ended up having to beat one player and by then it was "thank you very much." This is on SS!