Dwayne Barry said:
Where are those numbers from? They're not in the CAS decision. Regardless, he would still be guilty of blood doping under the WADA/UCI rules.
No question about guilt. I agree that he's bad. There are big problems with the way the test is done, but none of those problems are relevant to Tyler: he was clearly doping and CAS was right to uphold the finding.
The detail is that foreign (transfused) blood stays in the bloodstream for a long time and is detectable for about 4 months after you get the transfusion. Typically, if you got a transfusion of one or two pints worth of packed erythrocytes that would increase your packed cell volume by something like 10-20% (there are about 10 pints in your body). This means that right after a transfusion, the test would find 10-20% of your blood in a separate immunological group.
Erythrocytes last around 120 days (4 months) so if you don't continue to transfust then the amount of foreign blood in your body will gradually fall off to zero. The fact that Tyler had only about 1.5% foreign blood in him means either that 90% of the blood from his last transfusion had broken down, meaning that the transfusion was several months in the past, or that he had recently transfused a tiny quantity of blood---no more than 75 ml, or around 5 tablespoons---which would be much too little to give him any athletic advantage.
None of this lets him off the hook,. but it does underscore why homologous transfusion is probably the stupidest way to cheat: unlike EPO or other drugs, transfusions boost your performance for maybe a month at most, but remain very detectable for four months or more, so you can be caught long after you lost the benefit.