Matt: I bumped this up over to the front page as it's good stuff from TFTribe once again.
Since Matt brought it up in his comments about the King's Bishop Stakes, and I read this about Acclimation's victory in the Pacific Classic, "Acclamation completed 1 1/4 miles on Polytrack in 2:00.61, a track record in the five seasons this track has had the synthetic surface. The only 1 1/4-mile main track race run at Del Mar each summer is the Pacific Classic," I figured I'd take a quick look at what a day of racing is composed of, distance-wise. I took a quick look at September 2nd and found that basically, the larger circuit tracks (Arlington, Del Mar, Ellis, Calder) average about 2 races per card of over a mile. Meanwhile, smaller tracks (Canterbury, Charlestown, etc) are around 1(-) per day. Now I didn't go all the way through every entry card on the 2nd (I do have a job) but when you figure that there will be around 10 races per day, you're looking at 10-15% of total races are at 9+ furlongs.
Obviously major stakes meets (Derby, Travers, etc) are going to emphasize the classic distances and will throw off the numbers. But when you consider that less than 5% of horses (probably really more like 1%) are going to be even remotely competitive with high level stakes horses, the number of Graded Stakes of 9+ furlongs can really be thrown away when considering your regular-type racing.
Smart people know that when you breed to anything you're just rolling the dice. Assuming there is some level of standard deviation of the results of a genetic match, you will want to center the capabilities of your horses at around a mile (well that is my theory). That way you're looking to either miss short of a mile (6-7f) and be centered around the majority of the racing in North America. Or you miss long, and you're at 8-10f and can still find a place to run. And if you're longer than that, you're probably just slow.
The big discussion around Derby time was that there are so few breeders that are shooting for Classic distances anymore. Why would you when 70%ish of non-stakes money is at a mile or shorter? Hell, the Rachel Alexandra-Curlin foal might run in 10k claimers, who knows. So when it's a total crapshoot anyway, you should play it safe. If you miss on a horse you're Breeding for the Belmont, then you end up with a horse that needs to be Western-broke as a pleasure horse.