Discussions: Safe at First

For our first official umpire forum discussion topic, we take a look at the 6/16/11 Mets-Braves game, during which Mets batter-runner Angel Pagan was called safe at first on a wide throw by Braves third baseman Chipper Jones (and an awkward tag by Braves first baseman Freddie Freeman). Raising the possibility of obstruction, UEFLer thexfactor264 (13th place, 8 points) wrote:

How about this play: (Video link)

What did Tom Hallion call? Did he call obstruction for the trip or did he think Pagan touched first base? Was this obstruction?

Discussion Point: What do we have here? Obstruction? Fielder in the act of fielding? Interference? Safe? Out? Missed call?

Because the possibility of Obstruction has been raised, this post shall be tagged with "Rule 7.06."