Carlo Ancelotti was impressed with how quickly James Rodriguez settled into the Premier League, but he wasn't surprised.
"It's football, the pitch is the same everywhere."
Moving to a new country, to a new league, to new surroundings with new team-mates and coaches, that has been used as an excuse for the slow start of many signings.
According to Ancelotti, it can take time for a player to reach his potential because these things have an impact, but "we are not playing a different sport".
Greatness always shines through, no matter where you play or who your team-mates are.
Many opposition fans snickered when Birmingham announced they were retiring Bellingham's No.22 shirt following the transfer, but the Midlanders knew that they had lost something special when Bellingham decided to join Dortmund.
As a result, they are not surprised by the start he has made in the Bundesliga, playing all of Dortmund's games so far and winning the Rookie of the Month award for September.
Mike Dodds is the head of the the Professional Development Phase programme at Birmingham and has helped bring through players like Nathan Redmond, Demarai Gray and Bellingham.
He still speaks to Bellingham every week, having spent the past few years nurturing his talent and believes that it wasn't until the teenager stepped up to the senior team that he really made a name for himself.
"He was just like any other kid. He had ups and downs, highs and lows, frustrations and success, but he worked extremely hard and has an unbelievable love for football," Dodds told Goal.
"He always wanted to win and always wanted to get better. That was always in his makeup. When he got to the age of 12, we thought 'this boy is actually half decent'.
"He was a talented boy, but there are loads of talented boys. In this industry, there has to be some luck involved as well.
"But you only really knew that he was going to be a footballer when he broke into the senior team. It's so complex, it's hard to say he was going to have a different career to any other boy.
"How he was different was in his love and his genuine childlike enthusiasm for football. Every boy that comes into the academy loves football, but he never lost the bug.
"Sometimes when they become teenagers, they get 'Kevin and Perry' syndrome, where you have to drag things out of them, but he still played and loved the game as a 16-year-old as he did as a seven-year-old.
"He just had an infectious love for football and that never diminished."
Similar to how Ancelotti views players, Borussia Dortmund head coach Lucien Favre does not think a player has to be a certain age to impress in a new league.
"With someone like him, I don't look at the date of birth," Favre told the Swiss Telegraphic Agency.
"I like the way he handles the ball, how he defends it. He gives us a number of tactical possibilities and has a fantastic presence.
"He can play as a number six or number eight, is a good passer and tries to put himself in scoring positions. He has the technical skills and a feel for space. That's why it's easy for me to work with such a talent."
Bellingham is part of Borussia Dortmund's new generation of players, with the club boasting one of the youngest attacks in Europe.
Precocious striker Erling Haaland, 20, is supported by 17-year-old Giovanni Reyna and 20-year-old Jadon Sancho.
On his Bundesliga debut, Bellingham provided an assist for Reyna, with the duo's combined ages adding up to less than Cristiano Ronaldo's age of 35.
In fact, Bellingham was just nine weeks old when Ronaldo made his senior debut for Portugal.
Wingers often are able to make an impact at a younger age thanks to their trickery and confidence, but it is rare to see someone so young in the engine room of a top club like Dortmund.
Twelve months ago, he was playing in the Championship for Birmingham City. Twelve months before that, he was a 15-year-old playing in their U23 squad.
He played 44 times for Birmingham last season and instantly became one of the team's key figures, showing maturity beyond his years.
"When he started playing with the senior team, he fitted in because players recognise good players," Dodds explains.
"If you go into a first-team environment and you're a good player, there's a respect there. I think once he got the opportunity in the first team, the players thought 'this boy is decent,' and that's why he fit in so well.
"When they saw they could trust him, they forget about his age. He just becomes another player.
"Once you've got the combination of being a good player and being able to trust them, then age becomes irrelevant.
"When you put players of that age in that environment, they can surprise you. But you have got to give them the opportunity first.
"Birmingham gave him the opportunity and 44 games at 16 is just phenomenal."
His displays for Birmingham saw Europe's elite come calling, with Manchester United battling for his signature before Dortmund convinced him they could offer him a better route to the top, having nurtured the likes of Sancho, Ousmane Dembele and Christian Pulisic and regularly given game time to teenagers.
"It's the perfect fit for him right now. He is going to continue to play games and continue on the next journey," Dodds continues.
"It's been well documented that he had plenty of choices, but knowing the boy the way I know him, he chose Borussia Dortmund on multiple questions he would have asked himself.
"Jude is an articulate and intelligent young man. You could probably put him in any dressing room and he would survive. He has very high emotional intelligence. Jadon Sancho, Gio Reyna are both English-speaking and I'm sure Jadon is a positive influence on him and how he copes in Germany.
"The proof will be in the pudding in two or three years' time. If it was the right choice, he will develop even further."
Having proven himself at Championship level and Bundesliga level, now Bellingham has the chance to show that age is irrelevant in the Champions League and is set to make his debut on Tuesday against Lazio.
"For every obstacle that has been put in his way, Jude has always been the same boy you find bouncing around the training ground," Dodds admits.
"Everything that goes in his path, he takes in his stride. Making his Champions League debut won't affect him and it won't go to his head. He'll still be the same boy."