United may be on course for Champions League qualification but their defensive vulnerabilities have been exposed on many occasions this season and they have relied heavily on the excellent form of goalkeeper David de Gea.
Louis van Gaal's men concede an average of around a goal a game and have the fewest number of clean sheets in the top five.
British trio Chris Smalling, Phil Jones and Jonny Evans have received a lot of criticism, but Neville feels they will improve if their injury problems subside.
"With the likes of Smalling, Jones and Evans we still have great hopes for that penny to drop," the former United captain told fanzine Stretty News.
"They're still developing and picking up injuries but when they stop and the penny drops you think: 'We've lived with his faults, development and now we're getting the benefit of it.'
"There is no doubt that Jones, Smalling and (Luke) Shaw have talent but they need experience, maturity and injuries to stay clear and they will fly."
De Gea has rescued United on several occasions this season, most notably against Tottenham, Everton and Stoke.
And he showed his worth again on Saturday at Loftus Road when he stopped a fierce drive from Charlie Austin in United's 2-0 win over QPR.
The constant chopping and changing of players in front of De Gea has not helped United, according to Neville.
"When I look at the United defence what it lacks is control," said the England coach.
"I see players that have talent but they're all individually working, not having controlled movements together of in-sync
That comes through understanding and from playing together.
"The reason that Chelsea have the best back four in the league is because they have good players, they play every week without many injuries.
"United have been absolutely blitzed with injuries in those positions for the last three years.
"At times they look all out at sea but you have to say in Louis van Gaal's defence, he has had Darren Fletcher in defence, Michael Carrick in defence with Antonio Valencia and Ashley Young as wing backs that have done well."
Neville seems to think United have the right manager to bring back the kind of glory days he enjoyed at Old Trafford, describing Van Gaal as "a great coach".
And he thinks the Dutchman has the perfect midfielder to orchestrate United's play in Michael Carrick.
Neville believes it is no coincidence that United have lost just once since Carrick returned from a serious ankle injury he suffered last summer.
"At the start of the season we were struggling, ask yourself who wasn't playing? Michael Carrick wasn't playing," said Neville, who played 602 times for the club.
"Now he's playing and the club went on a great unbeaten run.
"When you play with Michael Carrick you think there is authority, control, peace.
"When you are on a football pitch playing against Liverpool or Manchester City, you need peace around you as well
You sometimes don't want people running around.
"Scholes and Carrick together was peaceful
It was like going into a bar and hearing a piano playing.
Listening to some good rock is good and you like that too but sometimes it's nice to listen to a piano
Carrick's a piano."
Source : PA