[greymule]

I think that if the umps see the pivot man clearly off the bag, they do not give the out. But if the foot is close and it's hard to tell, the benefit of the doubt goes to the fielder. Often the fielder places his foot next to the back edge of the bag. Who knows for sure whether the foot is actually touching?

Many of what people think are "vicinity" plays are actually very quickly and accurately performed but give the illusion that the fielder was not on the base. Slow motion replay usually shows (as in the play at 1B where F3 appears to leave early) that the fielder did get the bag.