After reaching three of the last four Champions League finals, United never even made it out of the group stage this term.
Matters have hardly improved in the Europa League. Losses to Ajax, and then Athletic Bilbao last night [Thursday], mean they have suffered successive home defeats in Europe for only the second time in their history.
It is now going to take a monumental effort in next week's second leg with the Basque outfit to reach the last eight after being put firmly in their place at Old Trafford by an exceptional performance from a team currently a massive 30 points adrift of La Liga title favourites Real Madrid.
United have won just once in five European outings on home soil this term - against Romanian unknowns Otelul Galati.
But Neville feels it is part of a long-term process.
And, in an article for United Review, published prior to last night's [Thursday] game, he explained why it is only a repeat of what he went through as a younger player.
"The only way you learn European football is by playing and getting to the point where you start to absorb lessons," said the former defender, who is now making a successful career for himself as a pundit for Sky Sports.
"The manager knows he's got talented young players who are going to be at United for a number of years, and I think this year has almost been a step back to go forwards in Europe.
"The younger players in our squad will take a lot out of this season.
"There is a subtlety and attention to detail you need in Europe. Inches matter and whereas the Premier League can be a little more forgiving, in Europe opponents are more ruthless and more clinical in front of goal.
"I remember it when we were young lads too. It's just something you have to go through.
"It's an underachievement when you get to three finals in four years, then don't get past the group stage, but these are great experiences for the young lads.
"You get the fruits of your labour over time and these lads have huge talent."