Boston Red Sox starting pitcher Brayan Bello. Charles LeClaire-USA TODAY Sports

The Red Sox announced Sunday morning that the club has activated right-hander Brayan Bello from the 15-day injured list. Right-hander Josh Winckowski was optioned to Triple-A in the corresponding move. Bello is slated to start Sunday afternoon’s game against the Nationals at Fenway Park.

Bello, who will celebrate his 25th birthday later this week, has been on the shelf since late April due to a bout of lat tightness. Before the injury, the young righty had pitched solidly through five starts with the Red Sox this year with a 3.04 ERA and 4.06 FIP in 26 2/3 innings of work. 

He’s struck out a respectable 23.6 percent of batters faced and generated groundballs at a 51.3 percent clip during that time, although a whopping 19 percent of his fly balls leaving the yard for home runs stands out as a potential red flag in an otherwise impressive early-season performance.

That success on the mound has been par for the course among Red Sox starters this year, as the club’s 2.42 rotation ERA is the best figure in the majors to this point in the season thanks to excellent starts from the likes of Kutter Crawford and Tanner Houck

With righty Nick Pivetta having also been activated from the injured list in recent days, the club’s rotation is once again approaching full strength. While righty Garrett Whitlock remains on the shelf due to an oblique strain, righty Cooper Criswell has performed admirably in his absence with a 2.10 ERA and 3.94 FIP in 25 2/3 innings of work.

Making room for Bello on the active roster is Winckowski, who will turn 26 next month. It’s a somewhat surprising move given his success over the past two seasons. The righty was among the best multi-inning relief arms in all of baseball last year as he posted a 2.88 ERA with a 3.91 FIP in 84 1/3 innings of work across 60 appearances. He hasn’t quite kept that performance up this year, although he’s still enjoyed solid results with a 3.33 ERA and 4.27 FIP in 24 1/3 innings of work.

While that sort of performance would seem to warrant a spot in the club’s bullpen over other optionable arms such as Cam Booser, it’s worth noting that Winckowski’s peripherals have taken a significant turn for the worse this year. 

The right-hander has struggled to miss bats this year as his strikeout rate has fallen from a respectable 22.3 percent last year to just 16.8 percent this season. 

Meanwhile, his walk rate has ticked up from 8.4 percent to 9.7 percent and his ground-ball rate has dropped more than five points after sitting at a strong 51.2 percent last season. 

Those shaky peripheral numbers suggest that regression may have been on the horizon for Winckowski had he remained in the majors, a possibility supported by his elevated 4.53 xFIP and 5.43 xERA.

Going forward, Winckowski will head to the Triple-A level and look to recapture what made him such an effective reliever for the club last season while acting as an optionable depth arm for the club to lean on alongside former NPB starter Naoyuki Uwasawa

Meanwhile, the Red Sox appear poised to lean on right-hander Justin Slaten to fill the sort of high-leverage, multi-inning role they turned to Winckowski for last year. Slaten has impressed in 13 contests this year with a 1.74 ERA and 2.34 FIP in 20 2/3 innings of work.

More must-reads:

TODAY'S BEST
Oilers crush Panthers in Game 4, stay alive in Stanley Cup Final
Dodgers ace leaves game against Royals due to triceps tightness
Sam Mayer uses overtime restart to win Xfinity Series' return to Iowa
Liberty forward pushes herself into MVP conversation with big game vs. Aces
Tiger Woods makes big admission about his U.S. Open future
Cubs P 'Mike' Imanaga continues hot start vs. Cardinals
Celtics' All-Defensive guard reportedly could replace Kawhi Leonard on Team USA
Tee Higgins' contract decision adds pressure on Bengals in 2024
One-time Defensive Player of the Year open to reunion with former team
College baseball has become too regional for its own good
Three Padres prospects who should be untouchable in trade talks
Connor McDavid's history-making night helps Oilers stave off elimination
Astros scratch Justin Verlander as nightmare season continues
Watch: Oilers chase goaltender Sergei Bobrovsky from Game 4
Watch: Rockies third baseman takes advantage of Pirates laziness' to steal home
Pirates place young catcher on concussion IL
Watch: Game 4 of Stanley Cup Final gets off to chaotic start
Rockies 1B, former NL MVP diagnosed with internal oblique strain
NBA insider shares update on J.J. Redick's candidacy for Lakers HC job
Nationals hurler DJ Herz makes impressive history in third career start