Any way you measure it, Nate Eovaldi has had a terrific season for Red Sox

The 31-year-old righthander is having the best year of his career. Sustained health — Eovaldi’s 173⅔ innings rank fourth in the AL and represent the second-highest workload of his career — has allowed him to adapt his five-pitch mix to become reliable and at times dominant. He is tied for the AL lead in both starts of at least five innings (27) and outings of at least seven innings with no more than one run allowed (6).

“He has been one of the best pitchers in the American League,” said manager Alex Cora. “He’s a different guy than the one we traded for in ‘18.

“It’s not only about power and stuff. It’s about pitching and being efficient, understanding that effort, yeah, it’s great, but if you can control your effort, you’re going to be able to actually post most of the time.”

Eovaldi has been particularly good at Fenway Park. In 18 home starts, he is 6-3 with a 2.99 ERA — significant not just given the location of Friday’s game but also should the Sox host the Wild Card Game. Of course, Cole has been similarly dominant on the road, forging a 9-4 record and 2.95 ERA in 14 starts.

Eovaldi’s position atop the Fangraphs rankings reflects his excellence in areas that do not rely on defense, with his ability to limit walks (4.4 percent walk rate, second-lowest among AL starters) and homers (0.7 per nine innings, second), and a solid strikeout rate (26.0 percent, 14th) over a large workload putting him at the top of the heap.

Cole features an incredible 34.2 percent strikeout rate and low 5.6 percent walk rate, but has been more vulnerable to homers.

While Fangraphs pegs Eovaldi as the most valuable pitcher in the AL, other systems have reached different conclusions.

Baseball-Reference.com, which attempts to account for balls in play (adjusted for parks and defenses), has Eovaldi fourth in WAR (4.8), behind Robbie Ray (6.8), Cole (5.7), and Lance Lynn (5.0). Baseball Prospectus, which examines specific details not just of balls in play but also the quality of opposing hitters, parks, and weather, has Cole first (4.7), with Eovaldi fourth (3.4).

While those sites differ about where Eovaldi and Cole rank, all of them point to a conclusion similar to the one that Cora has reached regarding Eovaldi.

“He has done an amazing job,” said Cora.

Defense tightens up

Several factors have played into the seven-game winning streak the Sox will take into Friday. Among them: A defense that has done a much better job.

For most of the year, the Red Sox infield has been the most porous in baseball. Through Sept. 9, they had allowed a .274 average on ground balls, easily the worst in the game and far worse, in the estimation of Statcast based on the type of contact, than the .245 expected average on such balls.

Since Xander Bogaerts returned from the COVID-19-related injured list Sept. 10, allowing the Sox to move José Iglesias to second base, they have allowed a middle-of-the-pack .252 average on grounders (with a .241 expected average). Meanwhile, double plays — which had gone missing in August — have again become routine, with the Sox turning 11 in the last 10 games.

“I think positioning has been the key,” said third base and infield coach Carlos Febles. “The balls are being hit where the defenders are, we’re catching it, and we’re turning it. We are making the routine plays. That’s the key.

“We went through a tough stretch. But now, I think the guys are more focused on defense, and you can see it. They’re very active, very aggressive. We’ve got capable guys who can catch the ball and we’re doing that.”

Fenway spark

Entering the season, Cora emphasized the importance of reclaiming a home-field advantage, and as the Sox arrive at their final regular-season series at Fenway, their standing in the postseason race owes in no small part to their success in Boston. The Sox are 49-29 at home, a .628 winning percentage that ranks fourth in the big leagues, and 15-5 in their last 20 games at Fenway. They are 6-1 against the Yankees, with hopes of building upon that this weekend. “It’s going to be my first Yankees-Red Sox matchup here in Boston,” said Kyle Schwarber. “I’m definitely very excited to show up to the field on Friday and see the buzz. It’s going to be fun. I’m sure it’s going to be electric and I think we’re all going to be ready for the challenge. It’s definitely going to be a playoff atmosphere.”

Welcome back

The Sox officially reinstated outfielder Jarren Duran and infielder Jonathan Araúz from the COVID-19-related injured list and optioned them to Triple A Worcester — where both had been playing on rehab assignments. To create room for them on the 40-man roster, the Sox designated righthanders Yacksel Rios and Geoff Hartlieb for assignment … The Red Sox are 13-6 this month, a .684 winning percentage that would be their best September since 1977 (22-9, .710).