BOSTON — When former Red Sox president Dave Dombrowski signed Nathan Eovaldi to a four-year, $68 million extension after the 2018 season, he took a lot of flack. Eovaldi was a World Series hero, yes. But could the oft-injured starter stay healthy and prove himself a worthwhile long-term investment?

With the benefit of hindsight, maybe Dombrowski should have gotten a lot more credit.

Three years into that four-year deal, Eovaldi has solidified himself as one of Boston’s most valuable players. The 31-year-old is in the midst of a career season, ranking among the American League’s top pitchers while earning his first All-Star nod, and he has also become a respected leader within the Red Sox clubhouse.

Most importantly, Eovaldi appears to have finally gotten past his long history of injuries, the result of years of work transforming his body and routine in hopes of becoming a more durable and reliable pitcher.

“He’s definitely worked very hard at that,” said Red Sox pitching coach Dave Bush. “A lot of it has to do with listening to your body and knowing when you need to back off a little bit, but also tailoring your workouts and your flexibility and everything else to make sure you can pitch. It’s not as simple as working more or working harder, it’s working smarter.”

Barring any unexpected developments, Eovaldi is on track to make all of his starts over a full season for just the second time in his 10-year big league career.

He has already surpassed his career high in strikeouts (147), and his 145.0 innings, 3.72 ERA and 3.6 Wins Above Replacement all rank among the best in the American League.

He also emerged as Boston’s stopper throughout Chris Sale’s recovery from Tommy John surgery. And this Monday he delivered a huge seven-inning performance in what wound up being a dramatic extra-innings win, one the Red Sox absolutely needed to have.

That all-around reliability, both on and off the mound, has made Eovaldi a role model for his rotation-mates, who raved about his leadership and the impact he’s had on each of them.

“He’s really dedicated to his work and it really shows when he goes on the mound with the consistency that he has,” said fellow starter Nick Pivetta. “And the way it helps us is we see it and we learn it and we copy it as well.”

Added Martin Perez: “He has a beautiful heart and he takes care of his teammates. I’m going to tell you he’s one of the best people that I’ve met in baseball and one of my best friends.”

Bush said Eovaldi isn’t necessarily the most vocal person in the clubhouse, but his words and actions carry great weight, especially with his younger teammates. Eovaldi has just about seen it all throughout his career, and rookie Tanner Houck said having his perspective has been incredibly valuable as he’s worked to transition to the big leagues.

“When I initially was brought up, he was one of those guys that, me personally, I gravitated towards him right away,” said Houck, who added that Eovaldi has played a major role in helping refine his splitter. “Learning from him and what he thinks and what he was doing, I was able to learn and adapt it to where it fit me, but it goes back to asking questions and learning from it and watching it.”

None of this was a sure thing when Eovaldi signed his extension, and initially it looked like a huge mistake. The veteran righty did suffer through an injury-plagued and ineffective 2019 season, and he also missed three starts during last year’s pandemic abbreviated season. But since the start of 2020, whenever Eovaldi has taken the mound, more often than not he’s been the workhorse the Red Sox hoped he’d be in December of 2018.