Freak in what regard, thickness, bone, style, choke necked, all the above? You have used some good bulls, what is it about your calves that you don't like? Any reoccurring calf types from your cows?
By-Pass products, for energy or protein, allow more energy and nutrient absorption to the animal after the rumen, dairy cow rations have utilized these supplements for years. The key, in your case potentially, may be "energy", be sure that a few weeks leading up to calving you are supplying...