One of the first things an umpire is told after learning the "Big 6" mechanics is the importance of T I M I N G. Here are 2 examples: one of of bad timing and one of good timing.
First, the bad. Here's the call where Buster Posie reaches first on an error
Baseball Video Highlights & Clips | NLCS Gm 6: Huff scores on a Polanco throwing error - Video | MLB.com: Multimedia
In contrast, here's Hallion's call on Howard's called 3d strike to end the game (and it WAS a strike):
http://mlb.mlb.com/video/play.jsp?co...ic_id=14871772
T I M I N G is everything