Pirates vs. Royals - Home-run overturned

[Rich Ives]

Originally Posted by MOofficial

I do not know how to imbed videos, so I have provided the link.

Marte's double | MLB.com

Can someone please cite a rule that would change this from a home-run to a ground rule double?

Is it a ground rule application or something else?

The ball did not leave the field in flight. Therefore it's a two base award.

IN FLIGHT describes a batted, thrown, or pitched ball which has not yet touched
the ground or some object other than a fielder.

The wall is an object other than the fielder so the ball is no longer in flight.

Each runner including the batter-runner may, without liability to be put out,
advance—
(a) To home base, scoring a run, if a fair ball goes out of the playing field in flight