I hope I can say this without sounding like a baseball snob with a false sense of superiority: The infield fly rule is not all that hard to understand
With either zero or one out, if the bases are loaded or there are runners at first and second and the batter pops the ball up in the infield, he's automatically out and the runners aren't forced to advance.
The reasoning is pretty simple: to prevent infielders from turning a cheeky double play in which they camp out under a pop-up, only to drop it on purpose to then force the runners already on-base into outs.
But with just a runner on first base, the rule doesn't apply, because there's almost nothing to gain by letting a pop-up drop and forcing the runner on first base out at second.
Almost nothing to gain.
However, if the batter is significantly slower than the baserunner, it'd be wise to have them switch places, no?
That's exactly what Detroit Tigers second baseman Ian Kinsler did on Sunday, when he dropped a pop-up struck by the slow Tyler White so he could force the fleet-of-foot Colby Rasmus out at second.
Even the announcers don't know the rule. They're so bewildered by the effectiveness of the maneuver, they wind up sounding like Father Pat after he sees an alley-oop for the first time.
The video from another broadcast shows that first base umpire Carlos Torres originally called White out on account of the infield fly rule, before congregating with his co-workers, who had to teach him what he should have learned in the third grade.