How did this happen?

To call the result of the Kentucky Derby an upset doesn't begin to explain what happened Saturday at Churchill Downs when a 53-1 shot named Mine That Bird romped home by 6 3/4 lengths. This was a lot more than an upset; it was the most inconceivable result in the 135-year history of the race. An impossibility, that's what this was.

Paying $103.20 to win, Mine That Bird produced the second highest payoff in Derby history, but one can argue that he was a huge underlay at that price. The horse should have been 200-1 or 300-1 or somewhere in that neighborhood. He wasn't only because there are enough people out there who bet their favorite numbers, their address or a name that catches their fancy. There are probably some rich ornithologists out there right now.

That Bird was winless in two starts this year, failing in a pair of fourth-rate Derby prep races in New Mexico. His best Beyer figure coming into the race was an 81. His last race was 24 points slower than the last race of race favorite Friesan Fire. Friesan Fire finished 18th.

The horse Mine That Bird will be compared to is Donerail, the 1913 winner who holds the record for biggest Derby payoff ever. I can't tell you why that horse was 91-1, but he did run second in the Blue Grass in what I assume was his final Kentucky Derby prep. That's a lot more impressive than finishing fourth in the Sunland Derby, which is how Mine That Bird warmed up for his Derby.

Then there's Giacomo, a veritable pre-race superstar next to Mine That Bird. At 50-1, Giacomo had been the second-highest-priced Derby winner in history when winning in 2005, but he had at least finished fourth in the Santa Anita Derby, second in the San Felipe and second in the Hollywood Futurity. Mine That Bird had never even competed in races of that stature.

Perhaps the closest thing to Mine That Bird was 1971 winner Canonero II, who might have been 100-1 or more had he not been part of the mutuel field. Canonero II came to Kentucky by way of Venezuela, where he finished third in a $3,500 handicap race before the Derby. Like Mine That Bird, he crushed the field, winning by 3 3/4 lengths.

Then there's Count Turf (1951). Another member of the mutuel field, he failed to hit the board in the Flamingo, Everglades and Wood Memorial while prepping for the Derby, but ran the race of his life on the first Saturday in May, winning by four lengths. He, too, falls into the category of very strange Kentucky Derby winners.

But they get no stranger than Mine That Bird.

So why did he win and win in a runaway? It had to have been a combination of factors, starting with the track condition. He caught a sloppy track, which had to have moved him up. With a limited sample, sire Birdstone is producing 23 percent winners on the off going. (Ironically, Birdstone ran eighth in the 2004 Derby in the slop, in one of the worst races of his career). He is out of an unraced Smart Strike mare, and Smart Strike is among the better slop sires out there. His offspring win 19 percent of the time on wet tracks.

The other factor was jockey Calvin Borel. His ride was masterful. As he so often does, he saved every inch of ground, darting through narrow holes on the rail. As the field fanned out wide on the second turn, he had a horse bursting with acceleration who was taking the shortest way home. He made up several lengths on the turn.

As perplexing as the Derby result was, there's no doubt who the best 3-year-old in the country is. That horse just didn't run in the Derby. Rachel Alexandra's win in the Kentucky Oaks was stunning and brilliant. To win a Grade 1 race by 20-plus lengths under a hammerlock from your jockey, who happened to be Borel, is the type of thing that only the greats can do. She is not nominated for the Triple Crown, and her connections have said they're not interested in running against the boys.

Hopefully, they will change their minds. Rachel Alexandra would be a perfect fit for the Belmont, a race she would win. She should be given the chance.

In the meantime, we shift our focus to the Preakness. Can Mine That Bird do it again? Probably not, but who knows? He's already proven that in this crazy sport nothing is impossible.

Bill Finley is an award-winning racing writer whose work has appeared in The New York Times, USA Today and Sports Illustrated. Contact Bill at wnfinley@aol.com.