I think what you are seeing is probably the norm. Rearing queens is a tough business. There is only so much time to rear queens during the bee season. Ideally a queen breeder will check out the brood pattern of a queen before caging and selling. However this does not guarantee the queen will produce massive honey producing colonies. Queen breeders simply do not have the time and resources to fully evaluate new queens in a production enviroment. Most queen breeders use instrumentally inseminated queens or select breeders from their top performing colonies. This helps with production predictability, but is never going to be anywhere near 100%.