Case Play 2014-4: Batter-Runner Obstruction Up the Line

HP Umpire Greg Gibson's obstruction call in Anaheim led to an A's protest in the bottom of the 9th inning of the Athletics-Angels game. With none out and none on, Angels batter Erick Aybar hit a 2-1 sinker from Athletics pitcher Dan Otero on the ground up the first base line as Otero and first baseman Brandon Moss simultaneously attempted to field the batted ball as Aybar fell to the ground, resulting in a ruling of obstruction by HP Umpire Gibson. Crew Chief Gerry Davis clarified post-game that the obstruction call was on Moss.

PU Gibson points at F3 Moss, ruling obstruction.

Replays indicate that F3 Moss ran into F1 Otero after which BR Aybar collided with Otero, who had fielded the baseball, causing Aybar to fall down as Otero retained possession of the ball and Gibson signaled obstruction. The call was confirmed after crew consultation with 1B Umpire Phil Cuzzi, 2B Umpire Will Little and 3B Umpire and Crew Chief Davis, prompting Athletics Manager Bob Melvin to protest the game.

Question: Is this the proper call and application of rules? Should this have been ruled incidental contact and a live ball out on the tag, interference, or obstruction? If the call was improper, was it incorrect because of an issue of umpire judgment or due to a misapplication or misinterpretation of rules (and which ones are they?)

This Case Play is of the Group variety and expires no earlier than the final out of the final regularly scheduled game Sunday, August 31. Participants may receive up to two UEFL points for discussion and solution.

Wrap: Oakland Athletics vs. Los Angeles Angels of Anaheim, 8/28/14
Video: Broadcasters reignite the "interference vs obstruction" drinking game on OBS call in the 9th (LAA)