For sure microdosing EPO and blood transfusions, steroids, growth hormones etc probably also various medications are unlikely to be behind the metoric rise in performance we're seeing - as you write. Someone posted a study here, showing carbon rebreathing to be a massively effective way of increasing hematocrit (probably in competition even, unlike infusions which you can't do every day and microdosing EPO which in competition (or generally, really) won't have a massive impact) and carbon rebreathing isn't currently banned by WADA - which goes to show why their list of banned practices isn't functional as a definition of doping, in my mind.