Kevin Garside: This is the year we'll all find out just how good Lewis Hamilton is

Whatever its genesis, the move is just what Hamilton needed

The cars are on their way, 22 million-dollar babies freighted across the world for the opening grand prix of the year. The third and final pre-season test closed in Barcelona yesterday, leaving observers with a jigsaw of clues to assemble before the lights go out in Albert Park 13 days hence.

Don't ask the drivers for a straight answer about who might blaze a trail in Melbourne. Their job is to obfuscate and dissemble, to play down their own performance and flag up a rival who looked quick on soft tyres and reliable on longer runs. The appeal of Formula One lies in its layered complexity. For every petrolhead with a nuanced grip of engine mapping and fuel-load algorithms, there is another for whom the driver is all.

One of the central plot lines features Lewis Hamilton, who, six years after his explosive debut, begins life as a Mercedes driver. Hamilton took a huge risk in electing to leave McLaren, a team richly resourced with a history of producing winning cars. Had McLaren met Hamilton's valuation of his own worth it is difficult to see why he would have left. The decision is dressed in diplomatic terms as a new chapter, a chance to build a dynasty at a marque every bit as steeped in racing tradition as McLaren.

In truth, it had everything to do with the position taken by McLaren patriarch Ron Dennis, whose stubborn refusal to meet the demands of a driver to whom he had paid €75m (£65m) over the previous five years decided matters. Dennis has never allowed emotion to penetrate the economics of the deal. We are about to discover how mad he was to let Hamilton go.

For Dennis the company is always more important than the driver. By definition, he feels that a combination of Sergio Perez and Jenson Button provides sufficient potential and insurance to cover Hamilton's absence. That ignores the pulling power of Hamilton, the value he adds just by sitting in the car, the interest he generates, the emotion, positive or negative, fired by being the unique presence on the grid that he is.

Button is a fine chap and a clear thinker. Ross Brawn described him as the equal of Michael Schumacher in a good car, an opinion formed after watching Button blast towards the world title in a Brawn during the early grands prix of 2009. But he does not have Hamilton's visceral charisma, nor his willingness to roll the dice when the car is on the edge. For a number of reasons, not least Hamilton's speed, there is a palpable sense of relief in Button that he has gone.

The move, whatever its genesis, is just what Hamilton needed. At McLaren he could never escape the empowering myth of Dennis, the idea that he progressed so far only because of the leg-up offered 14 years ago. Hamilton could never quite be his own man. He was always the project of Dennis, which rather ignored the talent, effort, commitment and sacrifice required to gain the attention of the big man in the first place.

Hamilton was always entirely his own work. The problems he has had in his Formula One career were rooted in the reconciling of instinctive sporting drives with the corporate demands of being a McLaren man. Gratitude has been at the heart of the tension, McLaren demanding it and Hamilton feeling it ever more reluctantly as his own power base grew. There was always going to come a point when Hamilton and Dennis would go head to head. Last year's contract negotiations were thus an expression of Hamilton's growing maturity in the face of Dennis's absolute power.

His Mercedes career began in a tyre wall in Jerez following mechanical failure on his first day of testing. On Saturday he ended his final test at Barcelona on top of the time sheets. Though Nico Rosberg posted his first win in China last year, Mercedes could not match the development pace of their rivals, undone as they were by a wind tunnel irregularity and management reorganisations. Though these continue, the aero department has done its job, producing a car with far better performance through the corners.

Yesterday it was Rosberg who led in Barcelona, suggesting that Mercedes might be competitive in a way Hamilton could not have dreamt when he signed at the back end of last year. This is Hamilton's opportunity to shift perceptions, to demonstrate on his own terms that he is a driver for the ages, worthy of the respect and even awe of his rivals.

Fernando Alonso identified Hamilton as his most dangerous rival no matter what livery he wears. It represents an acknowledgement that he was unable to give during their bitter relationship at McLaren in 2007, when the rookie spoilt what could and should have been a hat-trick of titles for the young Spaniard. It is now for Hamilton to underpin that testimonial with titles.

Gentleman, start your engines.