Boston Red Sox starting pitcher Nathan Eovaldi winds up during the fourth inning of a baseball game against the New York Yankees, Wednesday, April 17, 2019, in New York. Credit: Kathy Willens | AP

In some of their most desperate moments last October, the Boston Red Sox, a team that hadn’t known desperation all season until then, turned to Nathan Eovaldi. Each time, he rescued them — never more so than in Game 3 of the World Series, when, on one day’s rest, he delivered six innings of relief in an 18-inning marathon the Red Sox lost but served as the emotional pivot-point in the team’s triumphant series win over the Los Angeles Dodgers.

For all practical purposes, the 2019 Red Sox are facing their October right now. Unlike the 108-win version of 2018, whose American League East lead never dipped below six games after July 31, these Red Sox are facing a summer of desperation. At 53-44 entering Friday, they are 10 games behind the first-place New York Yankees in the East and three games out of a wild card, and have shown few signs of being capable of a sustained push.

And once again, they are looking to Eovaldi, their veteran right-hander, to rescue them. But this time, the degree of difficulty is much higher.

Eovaldi, a starter by trade but an ace reliever when the situation has demanded it, is expected to rejoin the Red Sox this weekend for a three-game series against the Baltimore Orioles at Camden Yards after having missed the previous three months with elbow and biceps injuries. And he will be doing so as the Red Sox’s primary closer — his mission to stabilize a beleaguered bullpen (20 saves, 18 blown saves) that has yet to recover from the free agent defections of 2018 late-inning stalwarts Craig Kimbrel and Joe Kelly.

Eovaldi’s return comes just as the Red Sox are preparing to face the most critical stretch of their season to date — perhaps their last best chance to make a move. After the series in Baltimore against the woeful Orioles, they face 14 straight games against the Yankees and Tampa Bay Rays — the two teams ahead of them in AL East — with the July 31 trade deadline looming toward the end of that stretch.

As if to underscore the high stakes — as well as to hammer home the notion that last year’s magic is long gone — the Red Sox, in one 48-hour stretch this week, jettisoned three key 2018 contributors, designating for assignment popular infielder Eduardo Nunez and demoting relievers Ryan Brasier (a breakout star in 2018) and Hector Velazquez to Class AAA. None had been able to replicate his 2018 production this season.

“You have to make adjustments,” Manager Alex Cora told reporters in explaining the moves. “We made adjustments last year, and we will this year. We’re at the stage now — I’ve been saying it all year: we’ve got to get better. . . . [The players] understand where we’re at and what we’re trying to accomplish. If it sends a message, it might be that you never know. Is it urgency? Is it panicking? I don’t know. I think they understand we’re trying to put the best roster [together], and this is part of it.”

Had the Red Sox sent packing everyone whose 2019 output has failed to match that of 2018, theirs would be a half-empty clubhouse.

Right fielder Mookie Betts, the 2018 AL MVP, is down more than 200 points of OPS (on-base plus slugging) from last year, and designated hitter J.D. Martinez is down 150 points. Steve Pearce, last year’s World Series MVP, has hit .180 with a .503 OPS when he has managed to get on the field at all. Ace lefty Chris Sale has a 3-9 record and sports an ERA (4.27) that is twice his 2018 figure. Right-hander Rick Porcello has a 5.27 ERA, which ranks 73rd out of 76 qualified starting pitchers in the majors. Those regressions have offset the impressive strides made by players such as shortstop Xander Bogaerts, catcher Christian Vazquez and third baseman Rafael Devers.

“We’re still [close] to a wild card, which is still a good position to be in,” Martinez said. “We haven’t really gotten hot yet. We go on one of our hot streaks like we did last year, and we’re right there. You get to those later months, now fatigue starts setting in, and I think it’s the veteran teams that know what to do in those situations.”

The looming presence of the trade deadline — toward the end of the critical stretch of intradivisional games — gives the Red Sox a built-in lever to shift their season in any number of directions.

While it seems unlikely they would trade away someone like Betts, a free agent at the end of 2020, longtime Red Sox fans may recall that the 2004 team, under similar circumstances, made the shocking move of trading away superstar Nomar Garciaparra on July 31, a move that paid off when the Red Sox recovered to win the franchise’s first World Series title in 86 years.

But even if, as seems likely, the Red Sox hold onto all their major pieces at the trade deadline, and maybe even add one or two, there is a sense of time running out for the group that won the World Series less than nine months ago. Martinez has an opt-out in his five-year, $110 million contract, signed in February 2018, that allows him to leave and test free agency this winter. If he exercises it, he would join Porcello, Pearce, second baseman Brock Holt and first baseman Mitch Moreland as free agents.

After losing two out of three games to the Dodgers at Fenway Park last weekend, the Red Sox fell to 18-27 this season against opponents with records of .500 or better — a damning statistic that suggests they are no more than a mediocre team, propped up by a bunch of wins over bottom-feeders. (The Yankees, by contrast, are 25-16 against .500-or-better competition, and the Dodgers 29-21.)

Eovaldi alone isn’t going to fix what ails the Red Sox, but a 10-4 stretch in those 14 games against the Yankees and Rays might. The 2018 Red Sox didn’t know desperation until deep into the fall, but the 2019 Red Sox, for as long as their season remains alive, will know nothing else.