[NewNCref]

I'm sure this is an easy question for you guys, but I'm a basketball official, and was wondering if you all could clear up a question I have about baseball rules.

Runners on 1st and 2nd with no outs. A ball is popped up so that it is easily playable by the shortstop. (a) The shortstop catches the ball or (b) the shortstop drops the fly ball.

I know this is an infield fly rule, and that the batter is out, regardless of whether or not the ball is caught. My question is, are the runners forced to tag up in either (a) or (b)?

Thanks for your help!