Rockies batter Michael Toglia's home run survived Replay Review in Colorado despite video definitively indicating a fan's glove made contact with Royals left fielder Dairon Blanco's glove while the ball was still in flight. Why did umpires in New York return a "call stands"? It's baseball's parallax.
The Official Baseball Rules Definitions of Terms state, "Spectator interference occurs when a spectator (or an object thrown by the spectator) hinders a player’s attempt to make a play on a live ball, by going onto the playing field, or reaching out of the stands and over the playing field."
The definition of playing field is further explained with OBR 2.01 and the definition of fair territory, which state, "that part of the playing field within, and including the first base and third base lines, from home base to the bottom of the playing field" (foul is similar [yet different]). Thus, the vertical plane along the warning track side of the outfield wall/fence serves as the playing field's diving line.
This means the top of the fence is fair game for the fan to attempt a catch or even to interfere with the fielder—effectively, there is no interference to consider unless the fan reaches out over the warning track, not above the wall itself.
OBR 6.01(e) states that if fan interference occurs, "the ball shall be dead at the moment of interference and the umpire shall impose such penalties as in their opinion will nullify the act of interference," including the potential of awarding the defensive team an out.
Upon Crew Chief Larry Vanover shipping this to Replay HQ, the standard to confirm or overturn a call is "clear and convincing" video evidence, the absence of which results in a call stands outcome.
The issue with reviewing this play at Coors Field is a similar issue at other parks, too, in that the replay camera angles all suffer from a degree of parallax illusion, which creates uncertainty and fails to meet the clear and convincing standard.
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, measured by angle of inclination between two lines. Parallax effect occurs when viewing from a certain angle creates an illusion that something has occurred (such as, in hockey, a puck crossing a goal line) that upon viewing the play from a more definitive angle—namely top-down—conclusively demonstrates the initial impression was incorrect.
Because the fan's hands were in the air, parallax effect made it difficult to judge the fan's position relative to the playing field boundary. Accordingly, even though it might look at first glance as if the fan definitively reached over the playing field and contacted the fielder and ball at that point, the Replay Official could not be certain that this view was free from parallax illusion, and returned a call stands verdict due to this uncertainty.
Thus, to Royals manager Matt Quatraro's statement, "I don't know what the explanation was, and whatever it was, it's going to be a bad explanation," there you are—through science.
Video as follows:
