The 4-2 home win over rivals Manchester City on Sunday exemplified United’s recent transformation after a testing and unconvincing first half to the campaign with the Dutchman.
And speaking on Super Sunday following the Red Devils’ victory, Neville says they are less likely to drop needless points against teams below them next season, giving them a better chance to challenge for the league title.
Neville said: “Next season, [Van Gaal] will look at games he’s dropped points in in this season and will think because that level of performance has come now, they could win those games next season.
“I think the confidence will be growing in the camp. There are people in that dressing room who have won titles, and they’ll get the feeling again that the performance levels and confidence is coming back.
Marouane Fellaini has been one of Manchester United’s biggest improvements this season
“That’s the first time Louis van Gaal, Juan Mata and Marouane Fellaini have seen Old Trafford properly today in terms of an atmosphere.
“It’s what Manchester United can create and that will give them enormous confidence. It always does when you win big matches.”
United’s last four performances, against Tottenham, Liverpool, Aston Villa and Manchester City, have been among their best of the season.
They now sit third in the Premier League, four points ahead of their city rivals, and have exceeded expectations considering their stuttering campaign up to spring.
They end this tough run of fixtures by travelling to face champions-elect Chelsea at Stamford Bridge on Saturday.
Neville added: “They’re getting so confident now. It is a fantastic four performances.
“Against Spurs, you were maybe saying: ‘Spurs were poor that day, they were flaky.’ So you were thinking: ‘Is that the real deal?’
“To go to Anfield and win makes you really sit up, because it’s a tough place to play no matter how Liverpool are playing, what point in the season it is, or what point Liverpool or United are in in their development.
“But to come here today, especially after City started well and went a goal up, that’s a proper performance.”