That is the view of Tim Vickery, who believes the Manchester United midfielder remains highly regarded in Brazilian football despite a European career that has taken him from Chelsea to Nottingham Forest, Strasbourg and now Old Trafford.
Santos came through at Vasco da Gama before moving to Chelsea as a teenager, but his development has been interrupted by a succession of moves and loan spells.
“Well, he needs to settle down and have a regular first-team place at a team,” Vickery told Football Presse.
“And so many of them, you know, they're loaned here and they go here and there and bang, bang, bang.”
Vickery believes Santos' best football in Europe may actually have come during his loan at Strasbourg, where he was able to play with greater regularity and responsibility.
“And the best football he seems he played at Strasbourg and no one really saw it,” he said.
His return to Chelsea brought another problem, with Santos competing for midfield places in a squad containing one of the club's biggest investments.
“He had a problem there at Chelsea because Moisés Caicedo,” Vickery said.
That makes United an important moment in Santos' development. The move is another major step, but Vickery's point is that the 22-year-old now needs to stop moving and establish himself somewhere.
The early signs have not been perfect.
“Now the first game didn't start very well for him at United, and he's, he's already, he's already on the bench.”
But Vickery then made an important distinction.
“There are high hopes that he can develop under Michael Carrick.”
Those are not simply hopes inside Manchester United. Vickery was talking about the expectations surrounding Santos in Brazilian football, where the midfielder's potential remains highly regarded despite his difficult route since leaving Vasco.
“I personally, I think he should have gone to the World Cup,” Vickery added.
That belief is based partly on what Brazil needed in midfield.
“I think they needed more lung power in that, that position of the field.”
It also provides an interesting comparison with Casemiro, although Vickery does not regard Santos as a straightforward replacement.
“There were good things about having Casemiro in. There were bad things about having Casemiro in.”
One major benefit was the effect Casemiro had on Bruno Guimarães.
“Having Casemiro in improved Bruno Guimarães immensely because it separated the functions.”
“It left Bruno more free to push forward, but Casemiro just didn't have the legs anymore for open space.”
That is where Santos could offer Brazil — and now United — something different.
Vickery believes Santos has the physical capacity to cover ground while also contributing to a midfield rather than simply sitting in front of the defence.
There is another connection with Casemiro. Vickery believes Casemiro himself had to fight against the Brazilian system because it did not initially value his ability to pass.
“Casemiro fought Brazilian football because he wanted to pass.”
Santos now has the opportunity to develop in an environment where those qualities can be tested at the highest level.
But first comes the part Vickery considers essential: staying in one place, playing regularly and turning the potential that remains so highly regarded in Brazil into consistent first-team football.
Manchester United is Santos' fourth opportunity in Europe.
Vickery believes it needs to be the one where he finally gets the chance to settle.