Sean Doolittle was face up and horizontal, about to back into the teeth of an MRI tube, when it all hit him.

“What team do you play for?” the MRI technician asked in Scottsdale, Ariz., on Wednesday. Doolittle almost said the Nationals. But if this physical went as planned, it would confirm a one-year, $1.5 million deal with the Reds. So he told the truth — “I just signed with Cincinnati” — before the technician pressed a button, the tube sucked him in and, with 80 minutes to spare, Doolittle had nothing to do but think. He closed his eyes and let the change sink in.

“It’ll come in waves,” Doolittle said this week, shortly after agreeing to a contract that’s still contingent on him passing the physical. “But that’s kind of the price you pay when you invest yourself absolutely 100 percent in everything, like I did in D.C., like I did with the Nationals. And I don’t know another way to do it.

“I wouldn’t have changed anything. The ups and downs, like, my experience there. ... I’m just so grateful for it, and I’m now ready to move on to the next chapter.”

But before he did, Doolittle and the Nationals discussed a reunion that never got too close to happening. In his retelling, the Nationals reached out at the start of free agency — some time in November — and expressed interest in bringing him back. Doolittle described himself as “attached to the Nats” in a way he shouldn’t have been. He wanted to make it work, he said, and stay with the coaches, teammates and staffers he won the World Series with in 2019. He’s from New Jersey and spends most winters in Chicago yet considered Washington his quasi-home.

As the winter wore on, though, Doolittle shifted away from that aspiration. Talks with the Nationals seeped into the new year. The sides even tentatively negotiated terms and money. Then the Nationals signed left-handed reliever Brad Hand to a one-year, $10.5 million deal on Jan. 24. Doolittle saw the “writing on the wall,” as he put it, and started to consider other options with more urgency.

The Reds were the first team to reach out in early November. Two members of their organization happened to work at the facility Doolittle trained at this offseason in Tempe, Ariz. Doolittle picked their brains on the culture, the pitching development and personalities in the clubhouse. He spoke with Reds pitching coach Derek Johnson and starter Sonny Gray, his friend from when they played together in Oakland. And that led him to Cincinnati over a few other offers.

“There’s absolutely no hard feelings here,” Doolittle said. “I’m not mad at the Nats. I could never be mad at the Nats. Are you kidding me? There’s a business side of this, and right out of the gate, we had financial discussions with other teams that was just better. It happens, and that’s okay.

“But I knew I wasn’t going to break the bank in free agency, you know what I mean? The money wasn’t the driving factor. I wanted to be somewhere where I felt like I could continue all the work that I’ve been doing since last summer, and the Nats were definitely on the shortlist of that. It just never really felt like it was going to come together.”

Last summer, Doolittle landed at the Nationals’ alternate site after yielding seven hits, three homers and five earned runs in five appearances. His fastball lacked life and velocity. He had bleak thoughts about his arm being permanently spent.

He had technically gone to the injured list with right knee fatigue. The idea was to give him a breather in Fredericksburg, Va., a chance to smooth out his mechanics and get on track. When he returned to Washington, he appeared closer to his usual self. But then he strained his right oblique Sept. 10 and was finished for the season.

Health and safety protocols kept him from passing through the ballpark to say goodbye, whether it was for the winter or for good. He instead wrote a letter to each staffer — from the clubhouse attendants to the video team — and dropped them off in the parking lot while gathering his stuff. The ending felt entirely incomplete.

“I definitely don’t want to wear out my welcome somewhere,” Doolittle said with a laugh. “I’m about to play my 10th season and had never had a say in where I played until now. And part of me thought, if I’m back in Washington, am I trying to exorcise some demons from 2020 and 2019? Am I trying to rewrite a narrative about myself? I got into the idea of having a clean slate.”

Doolittle spent a month rehabbing the oblique injury with the Nationals’ physical therapist. After that, he and his wife, Eireann Dolan, traveled to Scottsdale. He was throwing by the first week of November. In the months since, he has worked with high-tech cameras and programs to tweak his delivery and workshop pitches. He trained with weighted balls for the first time. He is learning what data is useful for him. He has learned a lot.

And the Reds, Doolittle noted, are known for cutting-edge pitching practices. Kyle Boddy, Cincinnati’s director of pitching, founded Driveline, a popular workout facility. Nate Irving, the Reds’ bullpen catcher, was one of Doolittle’s instructors this winter. The opportunity to build on what began in Fredericksburg and carried to Tempe was alluring to Doolittle. He feels ready to keep remaking himself.

“It seemed like I would be able to take the stuff that I learned this offseason and come into camp talking about pitching with these guys in the same language that they use,” Doolittle said. “I thought it would be a smooth transition. It’s going to be different, but I’m really excited about it.”