No disagreement here. I think that there are multiple studies confirming the efficacy of blood doping with more or less relevant procedure and its is easy to spot the flaws in the studies with inconclusive results.
Reasonable assumption and the consensus view on the subject. While I quoted a few blood doping research who warned about applying the results to elite athletes, my issue is not that much the gap of knowledge on how elite athletes react to blood doping, but that even the existing literature points to the direction that better trained subjects react less to blood doping. For instance, a 1987 review combined data of four blood doping studies and concluded the following:
Those studies were time-to-exhaustion tests, and while easily accessible individual-by-individual data is scarce, you can see the same pattern in time trial studies also. For instance, in 1981 there was a placebo-controlled double-blind blood doping study by Melvyn Williams, where blood infusion improved the final time of a treadmill 5-mile run on average by 44 seconds (~2.5 %).
The New York Times (5/4/1980) published individual-by-individual data of the twelve participants, and out of curiosity, I divided the data to two groups (slowest six vs. fastest six) and there is a difference. Whereas the "slow six" improved on average from 32:10 to 30:57 (73 seconds), the "fast six" only from 28:17 to 27:55 (23 seconds), ie. -3.8 % vs. -1.4 %.
Even the first time trial (2013) study with rEPO divided the groups to trained runners (mean Vo2MAX 60.3 ml/kg/min) and recreational sportspeople (51.6 ml/kg/min) and found that the elevation of Vo2MAX was higher in the latter group (6.8 % vs. 10.5%) as well as the time improvement (-5.2 % vs -6.3 %). And yes, the difference of the time improvement is miniscule.
Regardless of the fact that the mechanism of blood doping is well understood and that the data is somewhat scarce and slightly anecdotal, I can only see the pattern of diminishing returns when subjects are better trained and there is a possibility that the improvement is close to zero with elite athletes. I can not claim that this is the case, but it is a possibility. There might be several physiological factors that differ between elites vs. recreational subjects.
- The limiting factors ("bottlenecks") in the chain of hemoglobin saturation/delivery/peripheral utilization.
- It is also possible that elevated blood pressure associated with blood doping impairs the blood flow to tissues because athletes' hearts are already working closer to their limits.
I didn't present my case too well on the "raw data"-issue, but my case has been that whereas the research shows truly amazing (up to 6%) improvements in performance in relation to rEPO or transfusions even with relatively low elevations of hemoglobin concentration (~5-15 %), the raw on-field data doesn't fully support this notion and this raises serious questions how well the data can be applied to elite athletes.
It is interesting that recent Dutch rEPO-sceptics can quote none other than Björn Ekblom ("discoverer" of blood doping in 1972 who conducted the first rEPO study with athletes in 1989) from one of Ekblom's articles: