I'd say most of the powerful breeding operations aren't trying to produce outstanding milers, so I guess that tells us why we have had so few in recent years. Coolemore seem to have their sights set at about 10F, Godolphin are just quantity over quality, Shadwell seem to get lucky now and again without having a strategy as far as I can see. The Aussies seem to want sprinters and the Yanks dirt horses with a mixture of stamina and speed. I don't see much of a recipe in there for producing brilliant milers and most Guineas flops these days are usually dropped in trip to try sprinting or handicapping.