Sebastian Vettel may have suffered "burnout" from his time at a Ferrari team where there is "always friction", Grand Prix Drivers' Association chairman Alex Wurz has told Sky F1.
Vettel is leaving Ferrari at the end of 2020, and while he has shown flashes of his brilliant best in red, the five-year partnership between F1's four-time champion and its most successful team has so far resulted in zero titles.
Wurz, who heads up F1's drivers' body where Vettel is a director, had his say on the sport's big news during his appearance on Friday's Sky F1 Vodcast - believing the Ferrari "system" can take its toll on the drivers.
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"Sebastian is a friend of mine, but I didn't see it coming," said Wurz, who made his name in F1 with Benetton, McLaren and Williams before his role with the GPDA. "He keeps those cards always very close to his chest.
"If you look at the history of Ferrari, you have this first few years and months of big love and all these radio calls, all the emotions that come out of it, which makes Ferrari so beautiful.
"But at one point, even with Fernando [Alonso, who Vettel replaced in 2015], it seems like the whole system makes you go into burnout. Maybe the love is not there anymore, and that seemed to happen. But Sebastian hasn't spoken to me about that."
Watch the full Vodcast as Wurz and the Sky F1 team talk about F1's restart plans, driver market gossip and more.
Wurz joined Ted Kravitz, Paul Di Resta and Simon Lazenby on the Vodcast, and Ted pondered: "Do you think it's Ferrari's passion that is the great thing about them but also hurt them in some ways?"
"There's more to it than just racing passion," responded Wurz. "There is really the national pressure up on you and the drivers go through that.
"Ferrari are really demanding of the drivers, they really love you if you push them forward but if the success is not coming then suddenly that starts to backfire and they will also be protective about their heritage, work and quality.
"There is always friction, and that's not just for drivers, they have also changed team principals also over the years. And I think that comes with outside influence but also the lifestyle. That mixture seems to be tricky."
Ferrari won six consecutive F1 titles from 1999 to 2004 but have not won a championship in over a decade, despite its high-profile talented drivers.
"We look back at the (Michael) Schumacher, Ross Brawn, Jean Todt era, that group went in there and was so strong, could succeed, and could push that Italian pressure, whatever you want to call it, to the side.
"Since they left, Ferrari is behind its own expectations."