Moving Aoki allows the Brewers to shift Ryan Braun to right field and opens up left field for Khris Davis, a young power hitting outfielder Milwaukee wanted to make room for this offseason.
Smith, 24, pitched in 19 games and made one start last season for Kansas City, going 2-1 with a 3.24 ERA. He walked just seven and struck out 43 in 33 1/3 innings and opponents hit just .202 against him.
"Will Smith we have liked for a couple of years now," Brewers general manager Doug Melvin said. "We had the chance to acquire a 24-year-old big physical left-hander who we feel can be a part of our staff. We could not walk away from the opportunity."
Getting the news of the deal Thursday morning from Royals general manager Dayton Moore was a bit easier for Smith to take than the first time he was dealt, knowing a better opportunity awaits him with the Brewers.
"I like to think it's a good move," Smith said. "Obviously the Royals have an unbelievable pitching staff there and it was kind of a logjam a little bit. They gave me the opportunity and I'm very thankful for what they did for me. They let me get my debut and I can't thank them enough for everything.
"To be heading to Milwaukee and having a chance for the rotation, I'm excited for that part of it."
Smith has worked as a starter and a reliever during his time in the Royals organization, making 16 starts with a 5.32 ERA in 2012. That year he walked 33 batters in 89 2/3 innings and struck out 59.
Pitching in 28 games and making 10 starts for Triple-A Omaha last season, Smith went 6-4 with a 3.03 ERA in 89 innings. Smith carries a career minor-league ERA of 3.80 in 133 outings and 112 starts over six seasons.
"To be honest, I didn't really know my future there," Smith said. "I was happy just to be in the big leagues. When I was in Kansas City, the reporters there asked the same question: 'What do you want to do?' To be honest, I don't really care. As long as you are in the big leagues and you have a uniform, how can you care what you are doing?"
The Brewers have told Smith to come to spring training as a starter and that he'll have a chance to earn a spot in the rotation.
"I'm excited to get a shot back at the rotation," Smith said. "I've always enjoyed starting; I've done it basically my whole career. The fact that they are going to give me a shot at the rotation, I'm very excited for it.
"I enjoyed the bullpen, too. When the phone rang your adrenaline just shot through the roof. There are pros and cons to both sides, but if I have a uniform on and I'm in the big leagues I'll be happy. As long as we're winning, everybody will be happy."
According to FanGraphs.com, Smith averaged 91 mph on his fastball last season and also throws a slider, curveball and an occasional changeup. He went from throwing 6.2 percent sliders in 2012 to 29.9 percent in 2013, throwing less curveballs (21.7 percent to 11.3) and changeups (12.6 percent to 0.6).
The increase in sliders came after Smith spent time picking the brains of other relievers, trying to learn a role he had rarely been in before.
"The thing it boiled down to was 'I need to get this guy out ... now,' " Smith said. "As a starter you kind of set him up if you need to get him out later in the game. Out of the bullpen it was go get him now. That's why I kind of got more confidence in my slider, 'I can't leave this hanging, I've got to throw it.' I got more swings and it turned into being a pretty good pitch for me."
A native of Newnan, Ga., Smith still makes his offseason home in the city just southwest of Atlanta. He grew up a Braves fan idolizing Tom Glavine and John Smoltz and looks forward to pitching near his hometown for the first time.
When they heard of the trade, Smith's parents immediately ran to find Milwaukee's schedule to find out when the Brewers play in Atlanta.
"My mom is terrified of flying, like terrified," Smith said. "She won't do it. She gets claustrophobic and all that stuff. The fact Milwaukee comes to Atlanta, that's a good feeling to have your mom and dad sitting in the stands. My sister can come, too, so I'm excited about that part."
Originally drafted by the Angels in the seventh round of the 2008 first-year player draft, Smith played in the minor leagues with Brewers shortstop Jean Segura and right-hander Johnny Hellweg. Still close friends with Hellweg, the two began discussing spring training living arrangements Thursday morning.
But of course there's the obvious jokes about Smith's name and the references to "The Fresh Prince of Bel Air." Carrying the same name of a famous actor and rapper had led to Smith hearing every possible joke.
"Remember that ESPN commercial that came out with Michael Jordan?" Smith said. "That's basically my life."
Have all the references and jokes gotten old for Smith?
"That's a good question," Smith said. "I get them all the time. I think I've just learned to live with them. Some of them are funny, but some of them are just, 'Come on.' It's all in good fun. I mean, I'm a white guy named Will Smith. That's the way it is."
And while Smith considers himself a laid-back and goofy guy off the field, he doesn't carry the same attitude to the mound with him.
"I'm competitive," Smith said. "I don't get scared. I'm not going to back down from anybody. I'll attack you with my fastball and then use my breaking ball to try to get you out. Just establish the strike zone early, trust my catcher and go right at them."When it's my turn to pitch, it's my turn to pitch. There's no games once I have the ball in my hand. I'll be competitive, but you'll see a goofy side out of me here and there."
Signed as a free agent prior to the 2012 season, Aoki had two productive seasons with the Brewers. The club recently picked up his $1.9 million option for 2014 but became expendable with Davis' emergence last year.
Aoki, who will be 32 years old in January, hit .286 with eight home runs, 20 doubles, three triples and 37 RBI while stealing 20 bases for the Brewers in 155 games last season.
"Nori is a true professional and performed very well as a member of the Brewers," Melvin said. "This was a tough call because of what he brought to our organization on the field and in the clubhouse."
Considering the Brewers had never seen Aoki play in person when they signed him, the Japanese outfielder worked out well for Milwaukee. Aoki batted .287 with 18 home runs, 57 doubles, seven triples and 87 RBI in two seasons with the Brewers, stealing 50 bases with a .355 on-base percentage as the team's leadoff hitter.