Infield Fly Rule - Ball Drops

[ballingbob]

Gentlemen (and ladies),

I had a play the other night that didn't happen but I thought what if it did happen and had questions.

We had runners on first and second and a pop up in the infield while the infield fly rule was in effect. There was some confusion between the fielders and the ball almost dropped to the ground. If it would have dropped, the batter is out but are the runners still safe at first and second if they stay there since they are not being forced to run due to the batter being out? Or do they have to try to advance if it isn't a deliberate drop?

My thoughts were that they could remain on their bases and not have to run.

Thanks