Think of it like this. The reason for a force is that the runner behind you HAS to advance to your base, because there are no empty bases anywhere behind you. In your example (runners on 1st and 2nd), the step on 3rd base makes the guy who was on 2nd out. That leaves one runner at 1st, and the hitter (who has to advance to 1st). You can't have 2 guys on 1st, so that means the runner who started on 1st is forced to 2nd, with the hitter being forced to 1st. You can record an out at either base. In the situation today, once Cirillo tagged 1st, the hitter was out, which means none of the runners in front of him were being forced forward. The runner who would have been forcing them all forward had been eliminated, so the runners didn't have to advance, and there was no force play anywhere. I probably just made things more confusing.