SAN FRANCISCO — The headliners of the four-player return the Red Sox received from the Giants in the Rafael Devers blockbuster are, unquestionably, 23-year-old lefty Kyle Harrison and 2024 first-round pick James Tibbs III. But the member of the four-player package that may make the most immediate impact in Boston shouldn’t be quickly dismissed.

At first glance, Jordan Hicks looked like a throw-in — or at least someone included to offset salary — in the five-player deal completed between Boston and San Francisco last week. It’s true, as The Boston Globe reported, that the Red Sox chose Hicks (and the remainder of his four-year, $44 million contract) over paying off approximately $30 million of the money remaining on Devers’ mega-contract. With that choice came a delayed union of a team and player that flirted heavily just 18 months ago.

Following a 2023 season in which he logged a 3.29 ERA and struck out 81 batters in 65 ⅔ relief innings with St. Louis and Toronto, Hicks entered the free agent market as one of the most interesting arms available. Immediately, the Red Sox made a push for his services, according to sources — and were a preferred choice of Hicks from the outset of the offseason.

The Red Sox, like other teams interested in Hicks’ high-octane arm, had designs on signing him as a starter despite the then-26-year-old only having made eight starts (compared to 204 relief appearances) over five big league seasons. That intrigued him greatly. In the end, though, with the Red Sox willing to only guarantee a three-year deal, the Giants swooped in late in the process and won the bidding by guaranteeing a fourth season and upping the average annual value of their offer before agreeing to terms on January 12, according to a source. It was another lost bidding war on a long list of them in Craig Breslow’s first offseason as Boston’s chief baseball officer.

In San Francisco, Hicks initially dominated, first to a 1.59 ERA in six starts through the end of April and then to a 2.82 ERA in 67 innings through June 5. A rough five-start stretch in July and August led to him being sent back to the bullpen, where he turned in a strong August performance (1 earned run in 7 ⅔ innings) before shoulder inflammation limited him to just one outing in the season’s final six weeks.

New president of baseball operations Buster Posey decided to try Hicks in the rotation again to start 2025 but he logged a 6.55 ERA in nine outings before losing his rotation spot to talented young righty Hayden Birdsong. He then made four relief appearances before hitting the IL with toe inflammation on June 2. Overall, he owns a 6.47 ERA (but a 3.58 FIP) this season.

The Giants let Hicks go as a way to save some cash and also to give him a change of scenery, but they bid adieu feeling like they never got the most out of his talent.

“Jordan is a little bit of — I wouldn’t say unknown — but there’s just so much to like,“ said Giants manager Bob Melvin. ”The starting thing didn’t go exactly as he had planned, even though there was probably some unluckiness to it. But it’s a guy that throws 100 mph with a lot of movement, a good breaking ball and a split. It could turn a corner pretty quickly for him. He’s good.”

The Red Sox have been on a years-long quest to add velocity to their bullpen and in Hicks, who threw a 105 mph pitch in 2018 and averaged 97.3 mph with his fastball this season, acquired some. They also hope some of Hicks’ luck will turn. He hasn’t gotten as many swings-and misses (in the 6th percentile) or strikeouts (34th) as his pitch mix would suggest but also has a very high ground ball rate (58.7%, 96th percentile) and doesn’t allow many barrels (4.7%, 91st percentile). Theoretically, that ground ball rate should translate into outs but that’s no guarantee with the shoddy infield defense that has plagued the Red Sox for years.

Boston’s first goal is to get Hicks healthy and he’s on track to join the big league club soon. After pitching in Worcester on Sunday (and allowing a two-run homer), he’s scheduled to pitch again Wednesday for the WooSox. If that goes well, he could be active Friday.

Out of both need and timing, the Red Sox aren’t messing around with Hicks’ role. They have no designs, at least this year, on making him into a starter despite Hicks, according to people in San Francisco, having a burning desire to emerge as a rotation force at some point. Because Hicks’ stamina is not built up after two weeks in the bullpen followed by three weeks on the IL — and the fact the Red Sox could use another arm with Justin Slaten and Liam Hendriks both out — he will join the ‘pen as a setup option for lefty Aroldis Chapman. Boston could feature two triple-digit pitchers in the final innings of games.

“He is obviously is a proven back-end type arm,” said Posey. “He throws 102 (referencing Hicks’ fastest pitch of the year, at 101.7 mph) still. I think sometimes guys with that type of stuff, those shorter bursts are well-suited for them.”

It’s possible that both pitchers acquired in the deal could help the Red Sox in the big leagues soon. Harrison, who had made four turns in the Giants’ rotation before the deal, remains in Worcester and in track for his organizational debut Thursday against Scranton. He could emerge as a rotation fill-in for Boston around July 4, potentially as a replacement for the scuffling Walker Buehler. When he does, his former Giants bosses will be paying attention.

“Harry’s gonna be good,” Melvin said. “There’s no doubt about it. Harrison had to be part of that deal.

“Harrison’s not an easy guy for us to part with,” Posey added. “A touted young lefty that we all saw a bright future for here. There’s real potential there with Kyle Harrison.”