"Sometimes you have to stop, make a plan and start again. Sometimes you have to do something different," Prost added.
The F1 legend believes Ferrari's problems can be traced back to "when Michael Schumacher left", while McLaren's decline began when Adrian Newey switched to Red Bull.
According to swirling rumours in Monaco, McLaren could be looking to boost its fortunes ahead of the works Honda partnership in 2015 by making a swoop for Fernando Alonso.
"Fernando would be welcome back at McLaren," McLaren 'supremo' Ron Dennis, who clashed so infamously with the Spaniard back in 2007, reportedly told the Italian press.
"You're surprised that I'm talking about Fernando? I don't have any problem -- the most important thing is for us to win again.
"In 2015 we have the Honda engine and we need a great driver."
McLaren's current lead driver, Jenson Button, was asked by Spain's AS newspaper if Alonso will be at McLaren next year.
"He has a Ferrari contract," the smiling Briton replied.
"Yes it would be a great challenge to have him as a teammate."
According to two British F1 correspondents, there may be some truth to the Alonso rumours.
Jonathan McEvoy, of the Daily Mail, cited 'sources' as he reported that 'meetings' have already taken place.
And The Times' Kevin Eason agreed that "It is an open secret that McLaren have approached Alonso".
However, while Alonso has sounded frustrated with life at Ferrari recently, returning to struggling McLaren might not be at the top of his wish list.
"I'm happy," he told France's L'Equipe. "I have a great life, I'm a Ferrari driver -- it doesn't get much better.
"A third title would be the icing on the cake for my career. So many great drivers have won three titles."
Flavio Briatore, close to Alonso throughout his career, said in Monaco: "Fernando has a contract with Ferrari, so it's out of the question to go elsewhere unless something extraordinary happens.
"He, like everyone else, has difficult moments, and like every driver he wants a competitive car, and he can't solve the problems of an entire team by himself," the Italian is quoted by La Gazzetta dello Sport.