NEW YORK -- Justin Dunn was the 19th overall pick in the 2016 MLB Draft by the Mets. He was their No. 3 prospect by '17, per MLB Pipeline, ahead of current Mets regulars Brandon Nimmo and Tomás Nido and even 2019 NL Rookie of the Year Pete Alonso. And in '18, Dunn was named New York’s organizational pitcher of the year after compiling a combined 3.59 ERA in 24 starts between Double-A Binghamton and Class A Advanced St. Lucie.

But when it came time for Dunn to make his first appearance at Citi Field on Monday night, the Long Island native was wearing a Reds uniform.

After a pair of high-profile trades -- first, the December 2018 deal that sent Dunn from the Mets to the Mariners for Robinson Canó and All-Star closer Edwin Díaz, and then, the March 2022 deal that sent Cincinnati’s Jesse Winker and Eugenio Suárez to Seattle -- the 26-year-old right-hander found himself suiting up for a Reds team that had waited a long time to see him pitch, too.

Having overcome a right shoulder injury that threatened his career before it truly began, Dunn made his first big league start since June 17, 2021, against his old friends in the ballpark he always dreamed of pitching in. Though he gave up three runs in 4 2/3 innings and took the loss in the Reds’ 5-1 defeat, there was so much more on Dunn’s mind than the results.

“I’m so thankful, man. God is so good,” Dunn said. “There were a lot of times through that process where I was wondering if I’d even be able to throw a ball again normally, and a lot of doubt crept in my mind. So I’m just super thankful [to have] the opportunity to come pitch on this mound, to pitch at home, to pitch in front of my family, to toe the rubber against some of my best friends and just enjoy the game and truly have fun playing.

“Wasn’t as sharp as I would have liked to be, obviously, but just to be back out there and get the jitters out of the way was huge.”

The day after that 2021 start for Seattle, Dunn went on the injured list with right shoulder inflammation. Two months later, he was transferred to the 60-day IL. That’s where he remained after joining Cincinnati during Spring Training.

Dunn finally completed an eight-start rehab assignment with High-A Dayton and Triple-A Louisville in early August, and on Sunday morning, he touched down in New York, knowing that he would be recalled in order to make his 2022 debut on Monday night.

“It was pretty ironic because the way I called my mom and told her that I got called up to pitch here on Monday, it was exactly how I saw it when I was playing for the Mets,” Dunn said. “So to be able to get off at JFK and have them pick me up from the airport and go home and have a nice home-cooked meal was a pretty special moment. And then to look up and have them there and see them all out on the field was pretty awesome.”

Dunn had what he described as a “football team” of family and friends -- about 50-60 people in total -- in attendance at Citi Field on Monday. (“Let’s just say I played for free today,” he quipped.)

Though Dunn didn’t have the pitching performance of the night -- that title belonged to Mets starter Chris Bassitt after he locked up the Reds across eight innings, allowing one unearned run -- he was able to shake off the rust and talk some trash along the way, too.

While Dunn hit the first batter he faced, Nimmo, and gave up a home run to the second, Starling Marte, he turned it around by retiring the next three hitters in order, including Alonso on a first-pitch lineout to center field. That’s the out that stuck with Dunn, as the two have been giving each other grief while competing since their time coming up with the Mets together.

“The first thing we talked about today was if I hit him, he was going to charge me and give me a bear hug, pick me up and run with me to first base,” Dunn said. “… And after every at-bat, I told him 0-for-1, 0-for-2, 0-for 3.”

To be able to have that much fun on the mound again was a victory in and of itself for Dunn. As he walked off the field in the fifth, he tipped his cap to his support system in the stands and then hugged the Reds’ training staff -- expressing his gratitude to all the people who made it possible for him to have the moment he so desperately longed for.

“I’m so thankful for them to get me over here and take their time with me and really treat me with care and love and do everything they could to get me back on the field,” Dunn said. “They helped me so much, and I’m eternally grateful for them. And now, hopefully, we can build in the right direction of getting back to where I was before I got hurt.”