Boston Red Sox catcher Jared Saltalamacchia appears to tag out St. Louis Cardinals Allen Craig at homeplate in the ninth inning of Game 3 of the World Series at Busch Stadium in St. Louis on October 26, 2013. Craig was called safe after an interference call at third base allowed him to take a base. St. Louis won the game 5-4. UPI/Bill Greenblatt

Boston Red Sox catcher Jared Saltalamacchia appears to tag out St. Louis Cardinals Allen Craig at homeplate in the ninth inning of Game 3 of the World Series at Busch Stadium in St. Louis on October 26, 2013. Craig was called safe after an interference call at third base allowed him to take a base. St. Louis won the game 5-4. UPI/Bill Greenblatt

So you’ve seen the replay over and over where Allen Craig trips over Will Middlebrooks, the Boston third baseman, and scores the winning run in game three of the World Series. You heard the announcers used the term, “obstruction.” What is the rule and how did the umpires interpret the call?

Obstruction is the act of a fielder who, while not in possession of the ball and not in the act of fielding the ball, impedes the progress of any runner.

Rule 2.00 (Obstruction) Comment: If a fielder is about to receive a thrown ball and if the ball is in flight directly toward and near enough to the fielder so he must occupy his position to receive the ball he may be considered “in the act of fielding a ball.” It is entirely up to the judgment of the umpire as to whether a fielder is in the act of fielding a ball. After a fielder has made an attempt to field a ball and missed, he can no longer be in the “act of fielding” the ball. For example: an infielder dives at a ground ball and the ball passes him and he continues to lie on the ground and delays the progress of the runner, he very likely has obstructed the runner.

Crew Chief John Hirschbeck with his explanation of the obstruction rule:

“Obstruction is the act of a fielder obstructing a runner when not in the act of fielding a ball. It does not have to be [the] intent [to obstruct], OK? Once he has the opportunity to field the ball, he can no longer in any way obstruct the runner.”

Third base umpire Jim Joyce on his call:

“When the play developed after [catcher Jarrod Saltalamacchia] threw the ball at third base, after the ball had gone straight through, and [Craig] had slid into third and stood up to attempt to go to home plate, everything was off right there. And when he tried to advance to home plate, the feet were up in the air, and he tripped over [Will Middlebrooks] right there, and immediately and instinctually I called obstruction.”

“[Middlebrooks’ feet being up in the air] didn’t play too much into [the ruling] because he was still in the area where the baserunner needs to go to advance to home plate. And the baserunner has every right to go unobstructed to home plate, and unfortunately for Middlebrooks he was right there. And there was contact, so he could not advance to home plate naturally.”