I don't doubt that that is what they would say. But, I believe that approach and a denial based on it would not be correct. Ideally, if I were appealing to the BCMR, I would provide what I think they want- i.e., as you suggest, evidence showing that the military made the condition worse more rapidly than natural progression.
However, if that evidence was not available or - even if it was- I would argue in the alternative that the presumptions were neither applied nor overcome. The burden of production (who has to produce the evidence)-though this one is complicated in practice- and the burden of persuasion (who has to meet the standards) are on the military. In the absence of evidence (citing to generally accepted medical principles), then the presumptions are not overcome. And if they did not apply the presumptions in the first place, this is legal error.
As to the "subtraction" of what was EPTS vice what was service aggravated, I would say that if you start out that on entrance the person was able to perform all of the activities required of him, but over the weeks or months that he was unable, then all of that disability is "service aggravated" and compensable.
Again, I don't doubt that the BCMR may well take the position that because "it happened, it must be right." But, I think anything that does not address how, by citation to generally accepted medical principles" that the presumptions are overcome, would be error. Now, if they get it wrong, the forum where this is addressed is in court. So, it may be a long haul to get what is due (assuming a win).
Another important factor is whether the applicant is applying just for correction of records to show he was retired or if he claims wrongful discharge based on failure to process him through the DES. Generally, I think it makes sense to claim both.
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