The return of one M Schumacher to Formula One this year has got me thinking. How quick will he be, and is his best still good enough? While failing to sleep the other night, I may have inadvertently devised a way to work it out.

It’s all thanks to his team-mate Rubens Barrichello, who drove the same car as Michael in 2005 at Ferrari, and also drove the Brawn/Mercedes Silver Arrow that Michael will inherit in 2010, albeit revised and updated for next year.

2005 was the last season that Michael and Rubens raced together in the same machinery. Using race results from the 2005 season as a basis – specifically those races where both Ferraris finished, and adding a notional 45 seconds for results in which Rubens finished a lap behind Michael – you can work out that, over a race distance, the German was on average 23.8 seconds quicker than the Brazilian.

If you apply that figure to race results from last year, things really get interesting. Let’s imagine Schumacher was running a third Brawn in the 2009 championship, and was performing at the same level as he did in 2005, relative to Barrichello. Finishing 23.8sec ahead of Rubens in every race would have netted him wins in Australia, Spain, Monaco, Italy, Japan and Abu Dhabi, as well as at the European GP at the Nurburgring.

In our alternative 2009 championship, Schumacher would have been on the podium in Malaysia, Singapore, Germany, China, and at Silverstone. And a few other points finishes would have left him with a final points tally of 120; Jenson Button’s real-world winning count was only 95. By the same logic, Schumi would have beaten our Jense 14 times out of 17. Scary, isn’t it? But then he is a seven-times world champ.

Before you cry foul, I freely admit that there are all sorts of holes in my accounting. It assumes that Michael could have come back last season and driven as well as he did in 2005. It assumes that Rubens hasn’t improved since 2005, when clearly he has. It assumes that the likes of Button, Barrichello, Vettel, Webber and Hamilton couldn’t have responded and driven quicker last season, if given a greater challenge. And it assumes that there were 23.8 seconds to find within all of Rubens’ full race distance performances in 2009 – and from a few, I’m sure that no-one could have driven faster.

And yet still it paints an interesting picture. The motorsport fraternity is currently debating whether Michael’s comeback will be a triumph or a folly; whether he will be able to compete with drivers practically half his age, or get the best from a car that’s so different from the one he got out of in 2006. On this evidence, I’d say he’s got every chance.