I don't have a problem with it, if the whole package is considered. So just because a dog can run fast in flyball doesn't mean breed to another dog that can run fast in flyball and hope the pups run faster.
But if the dog can run fast in flyball, has all clearances and is structurally sound, has a good temperament, then sure, find a like dog that has the same qualities or better and breed and place in flyball homes. Or whatever sport for that matter.
But if you are breeding for performance, you'd better KNOW structure and keep that in mind, and breed to improve on what you have over 'he has titles too' without thought. I see a lot of 'sport bred' dogs that are not what I'd ever own or touch because they act like they've just downed a gallon of coffee beans and are on some strange high. All of the time.
And not place the high drive over the top insane dogs meant for experienced die hard handlers with newbies that haven't ever trained before. Or breed hoping to get those handlers coming for pups. There's a line...