HILLSBORO, Ore. — Shortly after his second professional season in the Seattle Mariners system last summer, Louis Boyd swallowed hard and called Carson Vitale, the team’s minor-league field coordinator.



Boyd was done playing.



The 24-year-old infielder was a .240 hitter who had yet to make it out of Single A, but that wasn’t the determining factor in his decision to pull the plug on his playing career. Boyd just felt he had a different calling.



“I told him that I wasn’t going to play next year because my passion for coaching and helping others strongly outweighed my passion for playing,” Boyd said. “I wanted to get into it as soon as possible because I knew if I got into it early, I’d be able to set myself up for success and be able to learn from a lot more people at a younger age.”



Boyd lined up a graduate assistant gig at the University of Arizona, the school he left just two years earlier, but in...