The fundamental problem for me is not whether Shelby is innocent or guilty of intentional doping, but, considering all the shortcuts permitted by the WADA Code to anti-doping bodies, we simply cannot say, notwithstanding the CAS ruling, if she is an intentional cheat, or just being treated like one.
The significance of Ayotte's studies are what these studies say, versus what she represented to the CAS, both with respect to levels observed in research, and GC/C/IRMS values considered endogenous. None of the data in Ayotte's own published studies support her representations to the CAS, but they do support both Houlihan's levels as consistent with pork offal consumption and her isotope values as endogenous.
Was there a course-correction/pivot? Houlihan told us last June that the burrito was "the most likely" explanation. This doesn't convey 100% certainty, but just their best guess. I think posters here are just hopping from one misunderstanding to another, and blaming Houlihan again.
It is not an issue for me that Houlihan still doesn't know where the nandrolone came from. That is exactly what I would expect from an innocent athlete who doesn't know how it got there and couldn't prove what she thinks must be the most likely source. I think it is the exception, rather than the rule, that an athlete would be able to prove the source. How many times have I brought up the case of Simon Getzmann. Without the luck of having one painkiller from the same batch to test, and that test result coming back positive, he would have boarded the same train as Houlihan that railroads guilty and innocent athletes alike to a 4-year ban.
Before 2015, the athlete did not have to prove "not intentional", and athletes were still sanctioned under the WADA rules. But for cases of possible pork ingestion, we don't even need to go there -- the TD2021NA explicitly foresees that pork offal ingestion can both produce the levels in Houlihan's samples, and corrupt the GC/C/IRMS values, making them unsuitable for endogenous/exogenous determinations. For these low levels, consistent with pork ingestion, it is well within existing WADA rules and guidelines to declare the result an ATF, and collect more data, whether through increased target testing or through optional pharmacokinetics, to eliminate the uncertainty.