In 2025, right-hander Jack Sinclair was invited to Nationals Major League Spring Training. He began the season in Triple-A Rochester, but was sent down to Double-A Harrisburg that July for the remainder of the year.
This year, Sinclair was not invited back to Major League camp. He spent his Spring on the Minor League side and returned to Rochester for the majority of the season.
And yet, Sinclair concluded the month of September having made his Major League debut – and a positive impression on the Nationals as a late-inning reliever.
“I told Jack … that I'd be lying if we thought that he was going to be throwing leverage innings for us at the end of the year here when we're pitching pretty well out of the bullpen, and that's a testament to him,” said manager Blake Butera. “He put the work in.”
Sinclair, 27, appeared in 11 games out of the Nats bullpen after debuting on Sept. 4. He went 1-0, posted a 2.45 ERA and earned one save across 11 innings.
His splits were impressive. Sinclair stifled right-handed batters to a mere .048 batting average.
“We used him in some big spots,” said Butera. “I think that you just get a good feeling when he takes the ball. We’ve asked a lot from him.”
Sinclair became a welcome addition late in the season for a bullpen that struggled with record-high blown saves. Butera was able to count on Sinclair in the eighth inning in particular, where he recorded a 2.45 ERA and held opponents to a .160 batting average.
“He's just the same guy every time, and he's not afraid of the moment,” said Butera. “I think that there's a lot to be said for that when you pitch in the back of a bullpen.”
In his 52 appearances with the Red Wings leading up to his big league promotion, Sinclair was 6-2 with one save and a 4.03 ERA. He recorded 74 strikeouts, including 72 as a reliever (tied for third-most among Nats Minor League pitchers), while allowing only four home runs.
Sinclair’s fifth full season of pro ball culminated with 71 1/3 relief innings thrown. It is his highest total since being selected by the Nationals in the 16th round of the 2021 Draft out of the University of Central Florida.
“It’s been pretty cool; it's been a lot of throwing,” Sinclair said. “But overall, I felt the best I’ve felt in a season, so that part's good. It's been a lot of fun, and I’m excited for the offseason, going into next year and building off of this year, and hopefully making improvements.”
In his September sample size, Sinclair threw a majority of sweepers and four-seamers, along with a sinker, slider and changeup. Opponents were 1-for-14 against his sweeper and 3-for-14 versus his four-seamer, which averaged 96.9 mph. The Nationals tasked Sinclair with continuing to increase his velo next season.
“[I want to work on] my body more, strength and gaining weight,” said Sinclair. “For me, it's hard to keep my weight on during the season. At the start of the year, I started where I wanted to, and then I’ve fluctuated the whole year. But getting that foundation back and getting stronger, maybe that helps more velocity. And then I want to improve my stuff, the sweeper, fine-tuning everything and getting it where I want for next year.”
Sinclair expressed a willingness to pitch whenever needed, and the Nationals turned to him in four of their last five games of the season. They hope to see more of that in 2027.
“It’s definitely good to have some success here and know that I can compete at this level and get really good hitters out,” said Sinclair. “That part’s good for my confidence, knowing that I can do that. I just want them to be able to call my name and they can rely on me to do the job they want.”