But arguably Australia's best player, the explosive left wing-back with a lethal left foot has been building for this World Cup since he learned to walk.
The Feyenoord sensation is poised for a tournament that could catapult him into superstardom and a berth in the Premier League, Bundesliga or other top league.
"He's unbelievable. He's had an amazing season, just getting better and better and better," teammate Harry Souttar tells AAP.
"I don't think he realises how good he is himself.
"He's just a great player, great guy to be around and just takes everything in his stride. There's nothing that fazes him and nothing's too big for him."
Bos plays on instinct: backing his speed to beat an opponent, going on incredible marauding runs then scoring or setting up a teammate.
"I've always been pretty fast, so from a young age, I would just run past people and still do it now," Bos said.
"Just dribbling people and running past them, and noticing that I'm a bit quicker than the normal person has made a way into my play style."
Right-back Jacob Italiano reckons that's an understatement.
"You see him knock the ball down the line and you see him go and you realise you need to keep up with him down the other side," Italiano says with a laugh.
"But obviously I love watching him play as well and being able to play with him is an honour.
"Watching him be so carefree and easygoing about how he plays his football, it's pretty special."
Souttar adds: "He's a pleasure to play with.
"Certainly on that left wing, when l hit a long pass that maybe is looking like a bad pass, his pace can make it look like a good pass.
"That's what I always say to him - 'keep running, get on the end of them!'"
Bos started to believe he could belong at the top level when he thrived under Patrick Kisnorbo, then the late Rado Vidosic at Melbourne City - two coaches that allowed him to express himself.
But the laid-back character from Melbourne's western suburbs got his first football education, along with younger brother Kasey, from his Dutch father Jacco.
"As soon as me and my brother could walk, he'd put a ball at our feet, and every day we'd go outside and kick the ball between ourselves," Bos said.
Kasey just joined Feyenoord's crosstown rivals Excelsior Rotterdam on loan from Bundesliga club Mainz 05.
"We'll be on opposite sides of the field, but I'll run to the other side of the pitch real quick and show him how to play a bit," Bos said with a laugh.
That plan could fall apart if Bos gets the big move everyone expects.
Bos pinches himself sometimes that he plays for his boyhood club Feyenoord - where he is adored.
"It's a feeling I don't think you get anywhere outside of sports," he said.
"To hear it and experience it is really awesome. I love it."
But the dynamic defender has made it clear where he wants to get to - either the top flights in England or Germany.
Everyone around him believes he can get there.
But now the World Cup is approaching, starting with Saturday's game against Turkey in Vancouver, Bos is locking in.
And his goals are simple.
"Win the games, see how far we can go, but just contribute as much as I can to winning those games," Bos said.
"If that's winning my duels, assists, goals - just whatever I can do to help.
"I'm just going game by game and see where the wind takes me.
"I'm in no rush to go anywhere, but if there's something, we'll see."
13°C