With the new Premier League season looming, United come into the campaign in the unfamiliar position of requiring drastic improvement.
Champions 12 months ago, United suffered a catastrophic 2013-14 under David Moyes - the Scot sacked before the season was out as United recorded a record-low Premier League finish of seventh
Van Gaal guided the Netherlands to third place at the World Cup in Brazil last month, and has now been tasked with returning the 20-time English champions to winning ways.
Docherty, who managed United between 1972 and 1977 - during which time he won the Second Division title and the FA Cup - believes the Dutchman's impressive CV will do little to prepare him for the weight of expectation placed upon his shoulders.
"Only time will tell because managing Ajax, Barcelona and Bayern Munich is a different kettle of fish from Manchester United," he told Perform.
"If you finish second at Old Trafford it's a bad season for you. It's the biggest and best league in the world but it's the most demanding.
"The good thing in his favour is he has the money to implement new signings, whereas a lot of managers don't have that."
Even so, after missing out on European qualification altogether in 2013-14, Docherty believes a top-four finish and a return to the UEFA Champions League will be United's aim this time around.
"Top four I think is achievable. And, if he gets that, he'll have done very, very well indeed and then he can kick on from there," he said.
"He's brought in his own staff. I think there's been far too much made of the class of 92 - I think there's too much sentimentality in that.
"Van Gaal's done well, he hasn't come in and panicked, he's taken his time. He's sussed out the strengths and weaknesses of the players that he's been left with and so far he's done a very good job."
