What's made this call controversial is the fact that something very rare -- likely unique -- happened: the ball was within the field of play when it was interfered with -- yet the fielder's only chance to catch the ball would have been
beyond the field of play. This still frame shows this clearly (you can see the trajectory of the ball nicely).
The right call was made, but the confusion by the general public and media is understandable due to the uniqueness of the situation, a direct result of the configuration of the stadium's wall and railing in Detroit.