The player had sparkled under his compatriot at the World Cup in Brazil the previous year and, with the Red Devils needing a replacement for Angel Di Maria, Van Gaal convinced the club's hierarchy that Depay would be the ideal signing.
His Manchester United
career started brightly, with the Netherlands international bagging a sublime brace against Club Bruges in a Champions League qualifier.
Ultimately, however, he failed to make the grade.
Man Utd: Bailly leading REVOLT against Mourinho with Arsenal keen
Man Utd news: Mourinho will not drop Matic because of one player
Van Gaal lost patience with Depay towards the end of his own United career, failing to include him in his squad for the FA Cup final victory over Crystal Palace.
And, when Jose Mourinho swaggered into town, that signalled an end to his time at the club.
Mourinho cut Depay loose, selling him to Lyon in January last year.
And, since then, the 24-year-old has gone from strength to strength.
Many United fans have been begging the club to re-sign the player, who has five goals and five assists from 13 Ligue 1 outings so far.
And his former coach, Cor Pot, believes he failed with the Red Devils because he made the move too young.
"I found Memphis especially a very positive boy", Pot told voetbalprimeur
"You already saw that it was a very great talent, maybe he went to Manchester United a bit too early, and that was all too fast.
'He was just a basic player in Eindhoven, Lyon was a good step for Memphis. it's fantastic now.
"He keeps on developing himself - not only as a player, but also as a person - Memphis gets a bit calmer, does not do any crazy things anymore, but at the time he was a bit shy.
'Of course you had that fuss with that hat extravagant behaviour. That seems a bit over now, I think he's doing fine."
Man Utd news: Mourinho picks between Alderweireld and Skriniar deals
Man Utd board think THIS about Mourinho and Pochettino amid job links
Pot also thinks Depay would has the potential to join another of Europe's elite in the future.
And he believes PSG, who are soaring at the top of the Ligue 1 title, would be a good destination.
"I think it's pretty good that he acknowledges it, it's a lot of self-confidence to say, 'This is not my ceiling. I want to go higher'.
'He's now in a strong competition and if he continues to do well, he can certainly take a step, to Paris Saint-Germain for example.
'I can see him there, or at English top club, he certainly can.'