His profile has soared during his time in England, with the overcoming of a difficult start seeing him emerge as one of the finest goalkeepers in world football.
De Gea has been a rare bright spark for United over recent seasons, with his consistency helping to paper over some of the cracks which appeared under David Moyes and Louis van Gaal.
He is impressing again this term under Jose Mourinho, but reports of a transfer to Madrid refuse to go away and Herrera admits that it is difficult to say with any certainty what the future holds for a man he plays alongside for club and country.
He told Jugones on the constant speculation: “I want to see him defending the goal of United. I hope so, but everything can change in football.
“I have tried not to get too much into the subject because it is not easy for him to be one day in one place and the next day in another. He learned a lot from it. It has made him more mature.”
For now, Herrera and De Gea are focused on ending the 2016-17 campaign on a high.
United have already lifted the Community Shield and EFL Cup under Mourinho, and they remain on course for Europa League success and a top-four finish in the Premier League.
Herrera added on the proven winner now in charge at Old Trafford: “He is a great team coach, I will remember him as a coach who has marked me.
“It is a myth of him being the defensive coach, we had to put a tag and [Pep] Guardiola was the offensive and Mourinho the defensive.”