He is the tenth umpire in history to serve as crew chief for three World Series.

Marsh was known for a comparatively small yet highly consistent strike zone, meaning he was among the most popular umpires for pitchers as well as hitters.

[citation needed] Marsh retired from umpiring following the 2009 season.

As of 2018[update], he is the Director of Umpiring for Major League Baseball.

In May 2008, Marsh underwent open-heart surgery; he returned to the field in August.