As I have always stated, cherrypicking studies with little knowledge about the entire body of literature is not the way to go. That cute little Ashenden study from the SCA-material (published also as a "letter to the editor" in Haematologica in 2006) is almost meaningless from viewpoint of how athletes microdosed, because it deals with subcutaneous injections, but athletes were using intravenous injections that are even more difficult to detect, a technical little trick that was first revealed by Floyd Landis only in 2010. I read a lot what David Walsh writes and usually like his books, but I almost laughed when I read how he described his work in Seven Deadly Sins: My Pursuit of Lance Armstrong (p. 411):
The reason I was able to keep reporting the Armstrong story was enough people cared about the truth. They spoke to me on and off the record. Exactly one week before Christmas Day in 2003, I sat with Jonathan Vaughters at a table in a Denver restaurant and he told me how riders were now micro-dosing EPO and how easily they were beating the new test.
In his obsession about exposing Armstrong, Walsh apparently had zero appetite for anything else than anti-Lance material and he either didn't care, didn't understand or found it irrelevant to actually listen to the details on how the dopers beat the system.
Even when Walsh and Michael Ashenden met now-and-then (SCA hearings), the latter revealed that he heard about the intravenous microdosing only in 2010.