It is always easy to get carried away by testing. Seeing a particular rider at the top of the timesheets, it is tempting to start constructing a narrative which sees that rider dominate the season, while writing off the rest. That, of course, is nearly always a mistake. And in the case of the second day at Buriram, Thailand, it is definitely a mistake.
That doesn't mean Marc Márquez won't be fast for the rest of the year, as well as Saturday in Thailand. He has won the MotoGP title in four of his five seasons in the class, so topping the timesheets was not, as one journo joked, because Michelin gave him special tires for his birthday. Márquez had been fast, and consistently so, through both the Sepang and Buriram tests so far. But the order behind Márquez probably doesn't reflect the true relative strength of the field.
The reason? Tires, of course. On Saturday, Michelin brought a new rear tire for the riders to test, after the rears used on Friday had shown some signs of degradation. The original allocation of rear tires were the same as used at Brno, Argentina, Sachsenring, and Sepang. The new tire was the rear used at the Red Bull Ring in Austria. That is relatively unsurprising, given that the place everyone compared Buriram to the first time they saw it was Austria. The different compounds in the Austria rear were better placed to withstand the stresses of Buriram, especially along the three successive straights in the tropical heat.