Before joining BSU, Coach Welsh was the first head coach for the boys lacrosse team at Plymouth North High School and had previously been an assistant varsity coach and junior varsity head coach for the combined Plymouth High Schools boys lacrosse teams. He was also a coach and executive board member for Plymouth Rock Youth Lacrosse as well as having coached multiple with multiple club lacrosse programs.

Coach Welsh grew up in the Baltimore area where he first began playing lacrosse at Andover High School in Anne Arundel County. He attended Anne Arundel Community College studying Architectural Technologies and later moved to Boston to attend the Boston Architectural College and pursue a career in architecture. Coach Welsh and his wife, Barbara, have two children in college and he currently works as Project Director for Boston Public Schools Department of Planning and Engineering.