Over the last five years the Red Sox have placed a clear emphasis on building up minor league depth, and at almost every turn the club has moved to bring in new prospects rather than deal any of the ones they already had.

This week, that dynamic started to flip.

Prior to this past Tuesday’s trade deadline, the Red Sox sent out 10 prospects over the course of five trades. Four of those deals brought back big league rentals who should help the club make a playoff push down the stretch. The fifth was essentially a swap of former first-rounders, replacing one highly regarded infield prospect, Nick Yorke, with a similarly intriguing starting pitcher in Quinn Priester.

The Red Sox didn’t trade any of their premier prospects, instead drawing heavily from their surplus of middle infielders and from those who will become eligible for the Rule 5 Draft this winter, but chief baseball officer Craig Breslow acknowledged the club paid a price to improve the big league roster.

“To improve the major league team we have to make difficult decisions and trade good players and those decisions are never easy,” Breslow said. “My guess is we traded a lot of major league talent today, but this is where we are and I think the team has shown they deserve to be reinforced.”

So where do the Red Sox stand now? If Breslow’s goal was to bolster the big league roster without gutting the farm system, he appears to have succeeded. The top prospects the club gave up at the deadline, Yorke and fellow infielder Matthew Lugo, ranked No. 12 and 13, respectively, on SoxProspects.com’s latest rankings.

Right-hander Ryan Zeferjahn and first baseman Niko Kavadas are both well regarded but don’t have particularly high ceilings. Infielders Cutter Coffey and Eddinson Paulino became redundant amid the organization’s huge glut of infield talent, and teenagers Yeferson Vargas, Ovis Portes, Gilberto Batista and Moises Bolivar are all years away from contributing in the majors.

Put it all together and the Red Sox still have exciting young middle infielders at every level of the minors, and you could make a case the club’s pitching depth is even better than it was before — at least in the upper minors — thanks to the Priester addition.

Selected No. 18 overall in the 2019 MLB Draft, Priester was regarded as a Top 100 prospect in 2021 and 2022 and was still considered one of Pittsburgh’s top five prospects when he made his big league debut in 2023. His numbers in the majors haven’t been impressive — he has a 6.46 career ERA in 94.2 MLB innings — but he’s continued to dominate Triple-A and has a number of tantalizing tools.

“He’s a guy I followed for a long time going back to my Cubs days, and he’s an extreme strike thrower and induces weak contact, keeps the ball off the barrel of the bat,” Breslow said. “He’s got a pretty deep mix, he throws strikes across five different pitches and we feel like adding some strength, working on the delivery a little bit and tweaking some of the pitches will hopefully get the best out of him.”

More importantly, he’s still only 23 years old.

“If you threw him into our Triple-A rotation I think he’d be among the youngest, if not the youngest, pitcher there,” Breslow said. “We firmly believe that if we get him in our infrastructure his best years are ahead of him and there’s a lot of potential to work with.”

For now Priester will start his Red Sox career in Triple-A, where he will immediately become one of the organization’s top young developmental arms. If all goes well he’ll stay there the rest of the season and potentially make a push for Boston’s starting rotation next spring, and even if he isn’t quite ready by then, he’ll remain under team control through the 2029 season.

But if anything goes wrong in the majors before then, he’ll also give the Red Sox an emergency rotation option, just in case.

“We’re in a spot where injuries have affected us, especially the last 15 days, but at the same time we don’t know what’s going to happen this month,” Red Sox manager Alex Cora said. “Maybe he’s a guy where in time something could happen here and he’s going to contribute.”

Triple-A: Casas, Grissom making progress

The most intriguing candidate for a big league promotion, Nick Sogard, finally got his call to the majors on Wednesday afternoon. Cora had been talking up the switch-hitting infielder for weeks, and Sogard earned the promotion after he hit 12 home runs with an .821 OPS in 89 games for the WooSox.

With him in Boston and several of Worcester’s other standouts now playing for other organizations, two of the most interesting remaining players to watch at Triple-A are also guys who might not be there much longer.

Triston Casas and Vaughn Grissom are on rehab assignments in Worcester, with Grissom having joined the club on July 20 while Casas started on Tuesday. Casas might not need long, as he is reportedly feeling good physically and now just needs to work on getting his timing back before returning to the majors, but Grissom’s situation is much more complex.

Grissom’s rehab assignment runs through Aug. 8, at which point he’ll either be activated and brought back to Boston or optioned to stay in Worcester. The second baseman has endured a nightmare season since being acquired this winter in exchange for Chris Sale and has been playing catch-up physically from day one thanks to a series of injuries. Understandably the organization is playing it slow so Grissom has all the time he needs to build himself back up.

Boston Red Sox second baseman Vaughn Grissom, right, looks to throw to first base to get out Minnesota’s Edouard Julien during the sixth inning of a game on May 3, 2024 in Minneapolis. (AP Photo/Matt Krohn)

The 23-year-old has begun to find his stride recently. Over his last five games entering Thursday’s doubleheader he’d put together a five-game hitting streak and was 6 for 20 (.300) with three walks. Whether or not he’s called up or optioned will probably also depend in large part on how David Hamilton performs in the majors. The 26-year-old has spent nearly the entire season with Boston and for several months ranked among the team’s top performers, but recently he’s fallen into a deep slump, batting .197 with a .511 OPS in July.

Double-A: Mayer placed on injured list

Marcelo Mayer has been tearing the cover off the ball all season, but his expected promotion to Triple-A may have to wait a bit longer.

Boston’s top prospect was placed on the seven-day injured list with hip irritation Thursday morning, though a Red Sox source said he just “needs a few days,” suggesting the talented shortstop shouldn’t be sidelined for long.

Top Red Sox prospect placed on 7-day injured list with hip irritation

The 21-year-old has been putting together a spectacular season in Double-A. In 77 games with the Sea Dogs, he’s batted .307 with eight home runs, 38 RBI, 10 stolen bases, 28 doubles and an .850 OPS while playing strong defense up the middle. He also participated in the MLB All-Star Futures Game and the associated festivities alongside Kyle Teel and Roman Anthony.

Teel and Anthony have also continued performing at a high level. Teel is batting .295 on the season, while Anthony is coming off a torrid July in which he batted .284 with five home runs in only 16 games. He went deep twice on Wednesday, and one of those was absolutely torched, coming off the bat at 116 mph. That’s one of the hardest hit balls by a Red Sox player at any level this year, including the majors.

Promising Red Sox prospect Roman Anthony is coming off a fantastic July. (Courtesy of the Portland Sea Dogs)

Breakout infield prospect Kristian Campbell is also continuing to rake, batting .380 in 42 games since his promotion to Double-A, and rising pitching prospects David Sandlin and Connelly Early were both recently promoted to Portland as well.

High-A: Romero on a roll

Mikey Romero’s professional career didn’t get off on the right foot. The former first-round pick endured a series of injuries that cost him almost all of his first full season, but now finally healthy he’s beginning to look like the impact player the Red Sox always hoped he could be.

The 20-year-old shortstop has been on an absolute heater for the Greenville Drive, hitting seven home runs in his last nine games. On Wednesday he went deep twice to bring his season total to nine, and over 19 games in July he batted .354 with a 1.163 OPS and 20 total extra-base hits.

Outfielder Miguel Bleis, who ranks as Boston’s No. 4 prospect according to SoxProspects.com, has also found his footing at High-A after a tough first couple of weeks. In 20 games in July, he batted .253 with four home runs, a .765 OPS and 10 stolen bases.

Boston Red Sox first-round draft pick Mikey Romero poses for a photo with Director of Amateur Scouting Paul Toboni after signing a contract with the club on July 25, 2022 at Fenway Park in Boston. (Photo by Maddie Malhotra/Boston Red Sox/Getty Images)

On the pitching side, Jedixson Paez has been dealing recently, posting a 1.02 ERA over 17.2 innings and four appearances in July.

Low-A: Arias earns promotion

One of Boston’s fastest rising international prospects recently earned a call-up to Low-A Salem. Shortstop Franklin Arias was promoted after batting .355 with a 1.055 OPS in 55 games in the Florida Complex League, and within his first seven games at Low-A he’d already homered twice, driven in seven runs and stolen two bases. He ranks as Boston’s No. 14 prospect.

Salem’s pitching staff was hit hard by the trade deadline, as Ovis Portes and Yeferson Vargas were both dealt for major league reinforcements. Portes and Vargas were also among Boston’s breakout performers in the FCL and had recently been promoted to Salem before being traded.

Jojo Ingrassia, Salem’s top pitcher this season, was also recently placed on the seven-day IL with left elbow inflammation. Prior to the injury he’d tallied 86 strikeouts in 53.1 innings while posting a 2.03 ERA.