Fister had been through a circus of a weekend already. On Friday, he was placed on waivers by the Angels, only to be claimed by the Red Sox and told that he'd be starting less than 48 hours later against the team that had just let him go.
No one knew what to expect from the 33-year-old, who hadn't started a Major League game since Sept. 28, 2016, as a member of the Astros.
After going six innings, allowing seven hits and three earned runs, it's safe to say that Fister had a positive 2017 debut, and earned a spot in an injury-riddled Red Sox rotation for the time being.
"It's definitely a good feeling to get back out there," Fister said. "I hold myself to a higher standard than what I had out there, so I've got some work to do. These next five days are going to be crucial for me to get back out there."
With the hectic and emotional weekend that Fister endured, Red Sox manager John Farrell says he couldn't have handled it much better.
"An overnight flight in here on Friday night and not a whole lot of sleep that night, but still he was ready to go today and he certainly did his job," Farrell said.
Even in a losing effort, the new arrival gained the respect of his teammates, who were happy to have him on their side.
"I've always thought he was a really good pitcher," first baseman Mitch Moreland said. "He threw a great game for us today, he throws fast, and he's always got a good game plan and really goes after it. Today was a great example of that."
"He likes to compete, I can tell," catcher Christian Vazquez said. "I like the attitude on the mound. He is pushing every pitch."
As for the team that parted ways with him earlier in the week, the sight of Fister on the mound was an odd one for some of his former colleagues.
This was especially true for Angels starter Parker Bridwell, who spent time with Fister when both were in the Angels' Triple-A affiliate in Salt Lake City this season.
"It's weird," said Bridwell, who earned the win on Sunday. "I was in the same clubhouse as him a week and a half ago, and we were talking about pitching and I was asking him certain things he did [in] his game and stuff like that, and next thing we know, we're starting against each other on the big league level. So it's just baseball. It's cool, though."
With his season debut in the rearview mirror, Fister now looks forward to adapting to his new home in Boston.
"It's definitely a little surreal yesterday coming in and being on this side of the ballpark," he said. "It's definitely a great feeling and being a part of this clubhouse is something special."
Evan Chronis is a reporter for MLB.com based in Boston.