Is it a home run if the outfielder falls over the outfield wall while making a catch?

• I vaguely remember seeing an outfielder falling over the other side of the outfield wall while making a catch and having it count as a home run, but that was over 10 years ago so I don't know if my memory is correct. A few years ago, Bobby Kielty also made a catch where he almost fell over that short wall in right field at Fenway and spent a while trying to make sure he didn't fall over. So it seems like the outfielder also has to stay in the field of play, is this true? But I've seen a lot of plays where players trying to catch a foul ball fall into the stands and it still counts as a catch and the batter is out. Why is there this difference?

• Answer:

  I think the rule is...it's an out if the fielder's momentum carries him over the wall. If he ran over a short wall, for instance, 15 rows up, it would be a home run since the fielder intentionally left the field of play. Otherwise its an out as long as he doesn't drop the ball. Rule 6.05(a) Comment: A fielder may reach into, but not step into, a dugout to make a catch, and if he holds the ball, the catch shall be allowed. A fielder, in order to make a catch on a foul ball nearing a dugout or other out-of-play area (such as the stands), must have one or both feet on or over the playing surface (including the lip of the dugout) and neither foot on the ground inside the dugout or in any other out-of-play area. Ball is in play, unless the fielder, after making a legal catch, falls into a dugout or other out-of-play area, in which case the ball is dead.