FORT MYERS, Fla. — The phone call left J.D. Martinez conflicted. In late November, a few weeks after Martinez hoisted the World Series trophy with the Boston Red Sox, he heard from one of the men responsible for guiding him to that stage.

Robert Van Scoyoc was calling to tell Martinez he had taken a job as the hitting coach of the Dodgers.

Martinez met Van Scoyoc after the 2013 season, as his career approached extinction with the Houston Astros. After toiling with Van Scoyoc and his coaching partner Craig Wallenbrock, Martinez rebuilt his swing, morphed into a fearsome slugger and ignited baseball’s launch-angle revolution. In the intervening years, Van Scoyoc had tip-toed out of the shadows. His work impressed the Dodgers enough to hire him to direct their offensive approach.

“I’m really happy for him,” Martinez said. “Obviously, I’m down about it, because I don’t get to work with him anymore.”

He added, “I wasn’t happy about it, at first. But I’m happy for him.”

The hiring of Van Scoyoc raised eyebrows because of his unorthodox background. He didn’t play baseball beyond Cuesta Community College. He has described his career as “very mediocre.” He built his resume out of a warehouse in Santa Clarita, Califirnia, where he and Wallenbrock worked with hitters such as Martinez and Dodgers utility man Chris Taylor.

As the most accomplished pupil of Van Scoyoc and Wallenbrock, Martinez has spent years hearing about their lack of credentials. He scoffed at those objections.

“That’s the most annoying thing to me,” Martinez said. “I’ve had it out with several coaches along the way, and I’ve said it: ‘I learned more from two guys who never played the game than six years in professional baseball.’ After Houston, where I didn’t learn anything. No offense to them. But just because you played the game doesn’t mean you know the game.”

The winter with Van Scoyoc and Wallenbrock converted Martinez from an also-ran into a force, and he maintained close ties with his instructors as his career took off. Since 2014, when the Astros cut him and he signed with the Detroit Tigers, Martinez ranks second among his peers in slugging percentage (.586) and third in on-base plus slugging percentage (.958). He swatted 45 home runs in 2017 with the Tigers and Arizona Diamondbacks, then signed a five-year, $110 million contract with the Red Sox last winter.

In his first season in Boston, Martinez galvanized a ferocious lineup and led the American League with 130 RBI and 358 total bases. The Red Sox rampaged through a 108-win season and bludgeoned the Dodgers in five games in the World Series.

The influence of Martinez extends beyond his own production. He believes the batting cage should be a scene for collaboration, where hitters trade ideas and offer tips. As a bilingual speaker, Martinez can deliver advice to the entirety of the clubhouse. He offers solutions, not dogma.

“It’s not about launch angle, or load with your hip, or whatever,” Manager Alex Cora said. “He recognizes swings. He has a way of communicating what he feels, in a very easy way.”

Martinez keeps his eyes open. An observation in 2013 altered the arc of his career. He had been an ineffective hitter for three years with Houston, so he spent hours studying elite hitters such as Ryan Braun and Miguel Cabrera. One day he noticed that the swing of teammate Jason Castro mirrored the swing of Braun. Castro told Martinez he learned the swing with Wallenbrock.

That winter, Martinez went to Santa Clarita. Wallenbrock, 72, had played college baseball in the 1960s, but dropped out to surf. His assistant Van Scoyoc was around Martinez’s age.

“He learned from me, and I learned from him,” Martinez said. “He taught me the mechanics of everything. I taught him the game plans and the strategy side of it. We both learned from each other. There were times when we got lost, and didn’t know what worked, and I was kind of the test dummy, because I was willing to be, and figure it out.”

In those three years with Houston, Martinez had posted a .687 OPS. That number jumped to .912 with Detroit in 2014 and, as Martinez soon became one of the game’s best hitters.

As more hitters learned from Wallenbrock and Van Scoyoc, teams took notice. The Dodgers hired the duo as consultants in 2016. Van Scoyoc spent 2018 as a hitting strategist with the Diamondbacks. The Dodgers brought him back this winter to replace Turner Ward, who left to become the Cincinnati Reds hitting coach.