This is so fascinating!
I could see USADA using a strategy of finding an athlete who is no longer at the top of his event, and threatening to expose him and drag his name through the mud unless he delivers as an informant.
So I picture a BTC athlete past his prime, agrees to pull a Judas on Shelby. One day, he makes a call to his contact at USADA saying Shelby used to have four vials of nandralone in the fridge and now has three — test her immediately.
Of course the informant athlete is someone who has access to the fridge because he also has vials there.
And USADA knows when to show up and what to test for, and knows not to accept any talk about false positives, because they have her own teammate as a witness and the blood test is just confirmation.
One thing that makes sense to me, is that working it that way is a good logical strategy after no smoking gun at Nike Oregon Project. From what Kara Goucher says, she wasn’t in a position to know who was doping with what, and when to test them. She was outside the loop and couldn’t bring anyone down, for doping anyways.
So you can picture why USADA needs their Judas, and needs him to retire quietly with a good reputation.