Education
After graduating from Miami Jackson High School, Mantrana attended Miami Dade for one season.
After graduating from Miami Jackson High School, Mantrana attended Miami Dade for one season.
He has held that position since prior to the 2009 season, when the program was known as the Texas–Pan American Broncs and represented the University of Texas–Pan American (UTPA). In 2015, UTRGV entered into operation after the merger of UTPA with the nearby University of Texas at Brownsville. The UTPA athletic program was inherited by UTRGV, and Mantrana kept his position through the merger.
He then transferred to Middle Georgia, where he helped the Warriors to the 1983 NJCAA World Series.
He earned was named to the All-Tournament team and was Most Valuable Player of the regional tournament while Middle Georgia finished second in the tournament. He then played two seasons at Louisiana State University for Skip Bertman.
Although Mantrana had been drafted several times previously (after high school and three times during junior college), he was not drafted at the end of his collegiate career. He signed a professional contract with the Detroit Tigers.
He played three seasons in Class A in the Tigers and New York Mets organizations before ending his playing career.
Mantrana began his coaching career at Miami Jackson High School, where he served for four seasons before moving to Miami Dade as an assistant. After one year, he earned the head coaching job at Saint Thomas. In his twelve seasons with the National Association of Intercollegiate Athletics Bobcats, the team appeared in the postseason nine times and earned three National Association of Intercollegiate Athletics World Series berths.
Over 95% of his players earned their degrees, and at least 25 went on to play professionally.
He compiled a record of 434–193–1. He became head coach at Texas–Pan American for the 2009 season, and led them into the Great West Conference.
With the dissolution of that league, the Broncs moved to the Western Athletic Conference, remaining in that league through the merger that created UTRGV.