HGG Community Forums

Matching paper levels, and, to a lesser extent, generations.
BA and SBA compare the foal's breeding ability score to that of both parents, and it must be roughly as good or better to pass SBA (BA allows through ones that are somewhat worse). So if the breeding ability scores of the parents are wildly disparate the foal will likely end up in the middle, significantly better than one, but significantly worse than the other and therefore failing SBA. Roughly speaking, the closer the breeding ability scores of the parents are to each other, the more likely the foal is to remain intact, because the easier it is for them to end up at least about as good as both, which is what you need to pass SBA.
We don't see the actual score, we see paper level and the results of comparison tests. The only benchmarks we really know for sure are foundations that are Perfect or ExPro- a mare and stud that are both ExPro's for instance, will have the same breeding score. So if you match paper levels and work for steady improvement down the generations, and then match generations, that's your best shot at getting intacts.
This last bit is conjecture on my part, but from my own observations I'm relatively sure that as quality and therefore paper level increases it gets more and more difficult to get intact foals, because the benchmark is higher. I seem to get more intacts from my Perfect foundations than my ExPro's, for instance, even though both should be exact matches. And it also gets more difficult in higher generations.