In more than three months since his last disastrous start for the Red Sox, Brayan Bello proved himself as an elite bulk-innings reliever.

Called upon to return to the role in which he struggled so immensely in early spring, Bello rose to the challenge in Monday afternoon’s series opener against the visiting Los Angeles Angels. His five innings were a grind and far from efficient, but making pitches at the most crucial moments, the homegrown right-hander compiled his best start of the year by far and helped the Red Sox to a 5-2 Labor Day victory.

It was not quite the “flying through the zone, strike, strike, strike” version of Bello interim manager Chad Tracy described pregame. Bello allowed four hits, walked two, hit a batter, and struck out seven; only 62 of his 103 pitches were for strikes. But it marked the fourth consecutive game in which Red Sox pitchers allowed two or fewer runs, a key metric for a squad with inconsistent offensive output.

“It wasn’t perfect,” Tracy began his postgame assessment of his starter. “It was five scoreless innings, which is awesome.”

“He got into some spots, obviously,” Tracy continued. “He made pitches in big spots (with bases loaded), and made pitches in three-ball counts, and kept those from being walks. … But he gave us five scoreless. He was really, really good in that regard.”

“He threw all his pitches well,” catcher Adley Rutschman said of Bello. “Just moved it around the zone, was unpredictable, did a really good job just like, playing kind of in-out, up-down with all his different pitch types.”

The opening frame was an achievement in and of itself, as Bello entered the contest with a 10.35 ERA over eight starts, including a particularly gruesome 16.20 ERA in first innings. Working around a two-out walk to left-fielder Wade Meckler, Bello hung a zero on the board in the first inning for the first time since April 29.

“I think it was important,” Tracy said of the scoreless first inning. “Step one was pretty good first inning, got out of the first inning. And I thought each one, each of those spots … you can see it building the confidence, him able to get out of that, and he gets out of another one later.”

“I say it was a very good outing,” Bello said via translator. “I kept competing against the batters, and I think I gave my team the opportunity to win today.”

Bello gave his team more than enough, in concert with Angels starter Grayson Rodriguez, who struggled through a start that was a full frame shorter and far messier. Rodriguez managed to escape a one-out, bases-loaded threat in the bottom of the first, but served up one opportunity after another. He struck out three batters and yielded five earned runs on six hits, including home runs to Jarren Duran and Rutschman, his former Orioles teammate.

After the Red Sox left the bases loaded in the bottom of the first, Duran became the third Boston batter to defy FanGraphs’ bleak preseason ZiPS projection that no one on the team would reach 20 home runs. Duran led off the bottom of the second with a first-pitch blast that put the home team up 1-0.

Boston Red Sox outfielders, from left, Jarren Duran, Eli White and Wilyer Abreu celebrate their 5-2 win against the Los Angeles Angels. Matt Stone/Boston HeraldBoston Red Sox outfielders, from left, Jarren Duran, Eli White and Wilyer Abreu celebrate their 5-2 win against the Los Angeles Angels. Matt Stone/Boston Herald

Injured first baseman Willson Contreras, who leads the team with 26 homers, and right-fielder Wilyer Abreu, second with 23, have already exceeded their previous single-season bests. Duran’s 425-footer, scorched 111.7 mph to deep right, also put him one shy of tying his career mark from 2024.

Boston quadrupled its lead moments later by winning the battle of Baltimore first-round picks. Rutschman, drafted No. 1 overall in 2019, clanged a 2-2 four-seamer from his former club’s 2018 first-round selection off the Pesky Pole for a three-run homer.

Eli White’s RBI single in the third scored the fifth and final Red Sox run. The lineup tallied nine hits, five walks, and struck out six times, going 3 for 10 with runners in scoring position and stranding eight men.

But after squandering their second bases-loaded opportunity, a compilation of back-to-back doubles by Caleb Durbin and Duran and second baseman Isiah Kiner-Falefa’s walk in the bottom of the fifth, the home team’s hitters went quiet. Left-hander Mitch Farris navigated through said minefield, then he and fellow southpaw Blake Weiman retired the Red Sox in order in the sixth and seventh, respectively.

White’s one-out single off righty Ben Joyce in the bottom of the eighth nearly broke up the sudden monotony, but White was out at second on the throw from Meckler to center fielder Jose Siri to shortstop Zach Neto. The sold-out crowd of 36,787 screamed “Safe! Safe! Safe!” as the play went under review, then booed loudly when the league office in New York did not overturn the call.

Moisés Ballesteros’ first-pitch leadoff homer off righty Wyatt Olds put the Angels on the board in the sixth, and Christian Moore’s RBI groundout brought Meckler home to score against rookie left-hander Alec Gamboa in the eighth, but the threats ended there.

Veteran closer Aroldis Chapman had the day off after three appearances in the weekend’s four-game sweep in Baltimore, including notching his 400th career save in Sunday’s finale. Instead, the longest-tenured member of the Red Sox pitching staff took the mound for a top of the ninth that saw the Angels lose three different ways.

First, as righty Garrett Whitlock completed a 1-2-3 inning with a strikeout-looking for Neto, and again when Neto unsuccessfully challenged the Strike 3 call. The third loss came in the form of the Angels’ official elimination from the postseason race; they will miss the playoffs for the 12th straight year, the longest active drought in Major League Baseball.

The Red Sox are 80-65, including five straight wins, and are the third American League team to reach 80 wins. They are two games back from the New York Yankees for the AL’s top Wild Card spot, and hold a six-and-a-half game lead on the rest of the league for the second of the three tickets.