The 25-year-old departed Orlando City SC following the 2021 season for Scottish Premiership side Hibernian FC, looking to make his mark overseas after a productive four-season run in MLS where he had 21 goals and 24 assists, putting himself on the US men's national team radar.
But in Scotland, Mueller said he dealt with more adversity than he has to this point in his career, starting with the sacking of the manager that signed him, resulting in fewer minutes than he'd hoped. Ultimately, he departed in early May for Chicago on a free move, staying for just five months.
"I wasn't playing as much, you know, it was really hard for me," Mueller told reporters on Wednesday. "But nonetheless I think that I went there for a reason. I learned a lot about the experience, in terms of being in a country, being in another culture, seeing how people from different parts of the world function in their day-to-day lives. I think that I tried to go into the whole thing with an open mind and tried to learn from the experience as it was, not even just on the football pitch, although I learned a ton about myself on the football pitch as a player."
Having gone through those challenges, Mueller said he feels wiser and more prepared as he embarks on the next phase of his career with the Fire, which marks a return to the area where he grew up.
The wide attacker is a native of nearby Schaumburg, Illinois, where he has fond memories of playing youth matches against one of his new teammates in homegrown defender/midfielder Mauricio Pineda.
"It was more about the mental grind that I was going through in terms of not getting the minutes that I wanted," he said. "The team wasn't doing particularly well either, we were losing a ton of games, and when you're over there in Scotland, football is No. 1 for all the people.
"And if you're not doing well on the football pitch, it's hard to have an outlet in any other way or shape. It seems like all eyes are on you guys, and when things aren't going well, people let you know about it. It's a much higher-pressure situation and all that, so just completely different. Different style of play, it's much more direct, just faster in terms of the pressing that is constant over there and the commitment to defend. I could go on and on about the differences and the things that I learned, but like I said, it was a positive experience because of how I came out on this side now."
For Chicago head coach Ezra Hendrickson, the hope is that Mueller will add a new element to an attack that has struggled to score consistently during their 2022 MLS campaign.
"Chris is a very good player. He's another player that we're going to want to get on the ball because of the things that he can do, on and off the ball," Hendrickson said. "His runs off the ball, his timing, getting behind defenses is very good. So that's someone who will help Shaq as far as having someone else to get on the end of things, because we all know what Shaq can do with the ball. And now we're starting to push the issue more about getting behind defenses, which will open up our game a lot more.
"So, Chris brings that opportunity for us, his 1-v-1 abilities, as well as his ability to get behind defenses and get on the end of some of these passes from Shaq and from Gastón [Giménez] and the guys from the midfield. We're very happy to have him and he's a great addition to the team."
Mueller echoed that sentiment, saying that he sees his ability to wreak havoc from out wide as a potentially ideal fit with the dynamic traits Shaqiri offers centrally.
Now, it's just about making it happen on the field.
"Shaqiri's obviously a really, really good player who's played at the top level all across Europe and whatnot," Mueller said. "When you have someone like that who has such good vision and is so good on the ball, he helps in the pockets. But in terms of I feel like off the ball, I can make some pretty decent runs in behind for him to pick out. And obviously with a player of his quality, he's got it in his locker to put a ball over the top or to slip a ball through. As long as I'm making good runs and looking to combine with him, I think that we can definitely work well together in that sense."