Tagging on a bobbled pop fly

[John Robertson]

All the above replies are correct. If you want to know the history of why this rule exists, it goes back to a 19th century ballplayer named Tommy McCarthy. When he started playing, the rule stated that a runner could legally tag up and advance only after the ball was caught--not touched. McCarthy made an "art" of juggling fly balls hit to him in the outfield. He'd bobble them while running toward the infield. By the time he'd actually caught the fly, he'd be standing within a few feet of the baserunner, thus effectively preventing him from advancing. That's why the rule was changed. Ain't sports history interesting?