Infield Fly Rule, the most debated rule in sports!!

Question
QUESTION: Greetings, I had an instance come up yesterday that I wanted to get clarification on (I was the umpire in this game).  Runners on first and second and one out.  There is a popup right behind the pitcher and I declare infield fly rule the batter is out.  Just after that, the pitcher goes two feet back and does NOT catch the ball....this is when the real fun started!  Both runners start to go towards each base and then the runner who previously occupied first base starts heading back.  The shortstop picks up the ball and fires back to first with the first baseman simply tagging the bag, but not tagging the runner.  Is this runner out (similar to a fly ball to the outfield) or does he need to be tagged out going back to first since the force (i.e. the batter) is out behind him.  Any help is greatly appreciated !!

ANSWER: Hi Mark,

No out, there is no force, the runner must be tagged for the out.

Mark

---------- FOLLOW-UP ----------

QUESTION: One more quick follow-up on this rule....in the case when an infielder does NOT catch the ball, does the runner's clock start ticking to tag up and advance when the ball hits the ground or some other time (such as when I yell Infield Fly rule).  I know on a pure tag up play, the runner can go once the ball IS caught and just wondering if the reverse applies when the ball is NOT caught.  Thanks for any clarification (again!)

Answer
Hi Mark,

An IF is just like any other fly ball except the batter is out.  If the ball is caught the runners must tag like on any fly ball.  If the ball is not caught the runners can leave when the ball is batted just like any other uncaught fly ball.  They don't need to wait for your call or the ball to hit the ground.  

Mark