Brian DeLunas played college ball at Missouri Baptist University. After college he joined the coaching ranks and worked in a variety of roles at the high school, college, and private training levels. The latter included:
- 2004-2006 Coach, Rawlings Prospects Baseball
- 2009-2014 Program director/pitching coordinator, Elite Baseball Training
- 2014-2017 Co-Owner/pitching coach, Premier Pitching and Performance
- June - end, 2017 Director of pitching development, CSE Talent
As is often the case with private instructors, DeLunas sometimes held multiple positions at the same time. Some of these included high school and college coaching responsibilities.
- 2005 Pitching coach Marquette High School
- 2006 Pitching coach Forest Park Community College
- 2007-2009 Volunteer assistant coach University of Missouri
- Summer 2009 Pitching coach Duluth Huskies of the Northwoods League
- 2011 Pitching coach Christian Brothers College High School
DeLunas was named bullpen coach of the Seattle Mariners for the 2018 season. He replaced Nasusel Cabrera, who had taken over on an interim basis for Mike Hampton for the second half of the previous season. The Mariners were looking for someone with a non-traditional approach and background to assist in developing their pitchers, complementing the work of former major leaguers Mel Stottlemyre and Jim Brower, respectively the M's pitching coach and assistant pitching coach. In 2019 the Mariners named DeLunas their Director of Pitching Development and Strategies to oversee the development of player-specific development strategies for every pitcher in the major and minor leagues. He returned to a bullpen coaching position in 2020, but worked remotely due to COVID-19. The Mariners released him after the season and replaced him with Trent Blank.
- Ryan Divish: "Mariners hire Brian DeLunas as bullpen coach", The Seattle Times, December 4, 2017.