At the end of 2017, Hyers joined the Red Sox as their head hitting coach. He and the Sox sought to revamp their hitting philosophy. Another new face, J.D. Martinez, was told by the Red Sox coaching staff to make Mookie his “project.” As Martinez watched Betts hit for the first time in the spring with his 2017 stroke, he said, “I don’t know that that’s going to work.” Betts was not offended. He wanted information.
Martinez signed a five-year $110 million deal with the Red Sox over the winter of 2017–2018, several years after reinventing his own swing and saving his career. Through 2013, Martinez had been a replacement-level big leaguer. In his first three years in the majors, he posted an 87 wRC+. He was a below-average hitter and a poor defender. He career was in jeopardy.
“You still talk to coaches, ‘Oh, you want a line drive right up the middle. Right off the back of the L-screen,’ ” Martinez told Travis in 2017. “OK, well that’s a fucking single.”
Martinez began to question why his best swing would result in a “fucking single.” The same winter as Turner, he sought a new swing. He found it in a facility in suburban Los Angeles with assistance from Wallenbrock and his protégé Van Scoyoc.
“I have this little theory,” Martinez says. “When I think about the best players, I think what makes people so good is when they have that insecurity about themselves … because they don’t want to fall off. It keeps them working. I feel like [Betts] had that little doubt. … Other guys have good years and they won’t make the change. He was like, ‘Dude, I have to figure this out. I don’t have it figured out.’ ”
Betts’ overhaul worked from the bottom up, too. Hyers and Martinez first stressed how his feet interacted with the ground. That was where the kinetic chain of the swing began. “I had to fix the ground before I fixed my hands,” Martinez says. “The engine is down there.” The Red Sox now travel with force plates that measure ground- interaction forces. The portable devices are set up in the tunnels of MLB stadiums so that hitters can measure their force and balance. They look something like large digital scales and, like TrackMan, were first popularized in golf. Betts had never thought about using the ground.
“He’d just been hitting away his whole life and didn’t think much of it,” Hyers says.
As I’ve written before, 90s analytics writers tended to underrate coaching and player development. The cutting edge work understands how coaching and statistical analysis work together. Babe Ruth’s lesson — that doing things differently than the way they’ve been done can make great leaps forward possible — keeps getting re-learned.