Should obstruction have been called? After all, Pillar clearly collided with Webb. Time for a Rules Review.
The baseball rules' Definition of Terms states, "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."
Regarding obstruction, the MLB Umpire Manual states, "the fielder must then avoid the runner," as relates to contact between fielder and runner that occurs off a batted-then-deflected ball not within the fielder's immediate reach. The MLBUM also states that batted-deflected obstruction may be nullified under a certain circumstance if the fielder "has a legitimate play on the ball." Based on this language, it is clear that baseball intends for responsibility of avoiding contact to lie with the ball-less fielder, absent these (batted-then-deflected ball) or similar extenuating circumstances (e.g., obstruction on a batter-runner trapped in a rundown between home and first base is only to be called if "the obstruction is intentional"). Thus, in most cases, "accidental" obstruction is still "obstruction."
It is clear, as relates to the Pillar-Webb play, that Webb did not have a legitimate play on the ball (by virtue of having gotten rid of it); thus it was unequivocally Webb's responsibility to avoid contact with Pillar.
However, if U2 ruled that Pillar, due to his momentary loss of balance in trying to quickly change direction, was not actually "impeded" by Webb—if U2 ruled R1 would have fallen to the ground or otherwise been imminently tagged out by Forsythe regardless of Webb's presence or even if he was not making a bona fide attempt to run the bases- if he was not actually making any "progress"—then the proper call would be "no obstruction."
If, on the other hand, Pillar was impeded from progressing back to first base, the proper call would be "obstruction." Replays appear to indicate Pillar was impeded from progressing to his base, if for no other reason than Pillar appeared to have been in the process of regaining his footing and was preparing to forge a path toward first base (or, at least, away from ballcarrier Forsythe).
Video: John Gibbons briefly argues, gets explanation from Ripperger & Joe West ("Read More")