Obscure Rule

[alanjbarnett]

I have a interesting rule question. There is a runner on 1st and 3rd, one out. The runners are off with the pitch, and the batter hits a line drive which is caught by the second baseman diving towards center field. The 2nd baseman throws to 1st to double off the runner going to second, but before the first baseman catches the ball, the runner from 3rd crosses the plate. Will the home plate umpire allow that run to score until the fielding team appeals the play? As I understand the rule, if the batter hit a fly ball in the same situation, the fielding team would be forced to appeal.

So the real question is, when will an umpire simply make the call, and when will they require the team to appeal a play.

Thanks in advance.