Merila was born in Litchfield, Minnesota, and attended University of Minnesota. While with the University of Minnesota, he played on the school's baseball team, and was named the Big Ten Conference Freshman of the Year in 1991 and Big Ten Conference Baseball Player of the Year in 1994. He also broke Minnesota single-season and career records for batting average with a .452 average in 1994 and a .393 career average. He was also selected an All-American second baseman in 1994.
Near the end of his senior year at Minnesota, Merila was diagnosed with a brain tumor, which was treated with radiation therapy. He was drafted by Major League Baseball teams twice - first, he was taken in the 10th round of the 1993 draft, though he refused to sign. He was next taken by the Padres in the 33rd round of the 1994 draft, beginning his professional career that year
He played for the Spokane Indians in 1994, hitting .253 in 54 games. In 1995, he played for the Idaho Falls Braves, hitting .284 in 56 games. Overall, he hit .268 in his two-year career. He also pitched in two games, posting a 32.40 ERA.
He retired from professional baseball due to a brain tumor. Following his playing career, he became the Padres' bullpen catcher. After the tumor returned in 2005, he was forced to give up his bullpen catching duties, however he still served as an aide to third base coach Glenn Hoffman.
- Ray Christensen, Dave Mona (2013). Tales from the Minnesota Gophers: A Collection of the Greatest Gopher Stories Ever Told. Skyhorse Publishing, Inc. ISBN 1613217005.
- "All-America". The Salina Journal. June 3, 1994. p. 14.
- BR Minors
- "Mark Merila". San Diego Magazine. September 2009.
- San Diego Union Tribune "Padres' Merila trades uniform for scouting job". San Diego Union-Tribune. March 29, 2012.
- Pat Borzi (July 30, 2013). "Still Here". Sports on Earth.