
Yankees batter Vernon Wells hit a foul popup behind home plate which went into the seats. While the ball was in the air, Mariners catcher Kelly Shoppach was following the ball in the air, and Muchlinski was moving out of the way when he lost his footing and fell down to the ground.
Fortunately, Muchlinksi was OK, and since many people were following the flight of the ball, they didn't seem him trip. At least, not until now.
Video via MLB.