“Surely, this is his last season in Formula One,” is a commonly heard refrain when it comes to Kimi Raikkonen’s future. Yet, year after year the 2007 world champion defies paddock speculation to stay on for one season more.

It played out the same way this year, too. Expected to drive into the sunset at the end of this season, the 37-year-old signed a contract extension in the build-up to this weekend’s Belgian Grand Prix that will keep him at Ferrari for, yes, one more year.

Already the oldest driver on the grid, few would contest the fact that Raikkonen is past his best and has been for some time now.

Make no mistake, he’s still quick. But those flashes of blinding speed that were such a hallmark of his McLaren years are a rare thing now. They’re still there but, like a fine vintage, are tapped only on rare occasions.

Sometimes too rare, as Ferrari chairman Sergio Marchionne himself acknowledged at the Austrian Grand Prix only last month.

“I think Kimi has got to show a higher level of commitment to the process,” Marchionne told reporters.

“There are days when I think he’s a bit of a laggard, but we’ll see. I am going to talk to him today, we’ll see what happens.”

A “laggard” is what Marchionne dubbed him. So why then have Ferrari chosen to retain him?

“You’ll have to ask them,” Raikkonen, typically taciturn, told reporters at the Belgian Grand Prix on Thursday.

“Honestly, the only thing is I was interested to be here next year. I didn’t really care what the rest is thinking.

“Obviously the team feels the same way. What is the reasons… you’ll have to go and ask them.

“I don’t know what else I could say.”

To be fair, from purely a performance point of view, if it made sense for Ferrari to keep Raikkonen after a season like 2015, then it definitely makes sense keeping him on for next year.

Of the three seasons Vettel and Raikkonen spent together as team-mates the 2015 season was when the Finn was most comprehensively outperformed. He has since upped his game.

But Ferrari weren’t assessing Raikkonen purely on performance terms. If they were, he wouldn’t be in the seat. He’s not pulling his weight in the constructors’ championship the same way Valtteri Bottas, for instance, is at Mercedes.

Ferrari, however, have traditionally placed more emphasis on the drivers’ championship than the constructors’ title and operated a policy of backing a clear number one.

In this case, Vettel is their ‘chosen one’. In Raikkonen they have a driver who is apolitical, won’t rock the boat, gets on well with the German and can support his title ambitions. Raikkonen is quick enough to act as the rear-gunner for Vettel but can’t tap the sort of speed necessary to beat the four-time champion consistently enough to trouble him.

Critics of Ferrari’s decision to retain Raikkonen have argued that keeping him denies talented young drivers a shot.

But, Ferrari traditionally doesn’t slot inexperienced drivers into their cars, preferring they cut their teeth further down the grid. As such, Ferrari-backed youngsters, like F2 championship leader Charles Leclerc, were never really in serious contention to replace Raikkonen.

Alternatively, Ferrari could have opted for drivers like Sergio Perez or Romain Grosjean as a stop-gap until their young drivers are ready. They’re experienced and could theoretically score more points for the team in the constructors’ championship.

But there’s no guarantee of that. Both are being run hard by their respective team-mates, in Perez’s case Esteban Ocon, currently in his first full season of Formula One.

Moreover, finally given a chance to prove themselves at a top team, a promotion will only fuel their ambition to win races, making them an unnecessary thorn in Vettel’s side.

Raikkonen’s been there and done that. He may not be at his best. He may not be the quickest choice of driver for that seat. But he is the driver Ferrari need.

And then there’s the added benefit, the cherry on the top, the prospect, however rare, of Raikkonen rolling back the years, breaking out the vintage and reminding Formula One of the devastating speed that still lies locked away in there somewhere.

“If I did not feel that I can go fast I wouldn’t be happy in myself,” the 2007 world champion, who last won in 2013, said.

“As long as I feel myself that I can win races and fight for championships, then that’s fine. When I don’t feel like that I will be the first guy to do something else.”

A Raikkonen victory — wouldn’t that be something special.