Lewis Hamilton will be crowned champion in Austin on Sunday if he wins the race and Vettel is no higher than third.
Massa, who drove for Ferrari from 2006 to 2013 and nearly won the championship in 2008, thinks that the expectation on the team to end its F1 title drought is playing a role in ramping up stress levels.
“We won the championship in 2007, and then after 2008, Ferrari started to have some issues – they never won again,” said Massa, speaking exclusively to Motorsport.com.
“Maybe when I left Ferrari in 2013 the feeling is similar to what they have now. Pressure to win, and they are struggling to keep the pressure down. They are struggling to do their job in an efficient way.
“I think definitely this year – although I am not saying they have lost the championship yet – but maybe they lost the battle at the end because of some mistakes, and maybe because they are feeling the pressure in a higher way compared to Mercedes which has a lot less pressure.
“Mercedes won the last four years. It makes it much easier to work with a title in your hands, compared to working where you need to win, and the chance to make mistakes is higher.”
Massa believes that the only way Ferrari can hope to turn things around is by strong management that keeps the team shielded from the external pressures.
“I think you need to find the way to work, the way to prepare things, in the most quiet way, in the most focused way,” he said.
“They are a good team and an amazing team, and I have to say, the car they managed to do is pretty good. They are doing a good job on that, but maybe some little things around are missing.”
Last week, former Ferrari technical chief Ross Brawn, who is now helping run F1, said he believed the team was struggling to remain cohesive after the death of chairman Sergio Marchionne.
“There is no doubt the shock of the sudden death of its leader, Sergio Marchionne, who had been such a strong reference in the team, will have a major impact, and that is totally understandable,” he said.
“Having experienced many crises myself during my time with Ferrari, what I know is that this is the time to come together, stay united and look ahead, without resorting to recrimination and playing the blame game.
“Drivers, engineers and management all win and lose together, which is an unwritten rule in every sport, not just Formula 1. Everyone at Maranello knows that. Now is the time to try and turn things around and finish in style a season that has many positives.”
Photo by: Le Mans Classic