This is the main thing I've been wondering about since Simona Halep got done for Roxadustat. She must've known how easily detectible that stuff is, so what exactly was she doing? You're right that it has a long half-life, I though the same thing, that micro dosing is impossible, but surely they must know that, and if they do, why have a laundry list of (some high-profile) people been busted for it.
en.wikipedia.org
I don't think these guys are doing stuff we haven't heard about, it's just that there is so much readily-available new gear around since the 90s that doping has evolved in a similar manner to aerodynamics. It's not really what they're doing more how they are evading the testing that I think is interesting. There must be some sort of masking agent, I think about Michel Hessmann, what he was taking must've been more incriminating than the diuretic itself, otherwise why just tank what would be a guaranteed positive on the chin. If Visma really thought he was done by contamination, why are they letting such a promising young talent go?
I know loads of people who take Cardarine (GW1516), anabolics, peptides etc. are decriminalised in England and you can buy it online. Because it's not actually a SARM you can properly stack it, usually with RAD140 or Osta, and it gives you a third lung. A friend of mine says he has to tell himself to stop working out because he can just go for hours at proper Mike Mentzer intensity without feeling tired. There are a ridiculous amount of drugs out there and easily available that these guys can take to achieve effects similar to blood doping without spiking the OFF-score.