This was highlighted back in 1999 but Zulle admitted to taking EPO when Festina were busted in 98. He served his suspension and came back in 99 to finish 2nd in the Tour. If he was allegedly not taking EPO or whatever, surely he should have been shouting how there was no need to take EPO as he was capable of achieving his best Tour performance without EPO. This never happened, I was one of those people who naively believed the Festina guys would not dope again in 99 until somebody made this very relevant point.
On the affects of EPO, Bjarne Riis was never a star, if he had been a good amateur, he would have turned pro with a bigger team than a small Belgian kermesse team. Riis never showed an ounce of potential as a GC rider until he moved to Ariostea and started working with Luigi Cecchini.
I also remember how many former mediocre cyclists starting producing performances in the 90s. Guys would suddenly go on hot streaks. Just to follow one thread, Moreno Argentin was one of the first riders to start working with Ferrari and he went through a real renaissance early 90s, then his entire Ariostea teams started winning, guys like Cassani, Cenghialta, Lietti, Furlan, Elli, Riis who had all been former domestiques and won nothing.
Argentin moved to a new team Mecair in 93, this is where Berzin, Bobrik turned pro. Dr. Ferrari was looking after half the riders on the team whilst another doctor Walter Polini was looking after the other half including Berzin, Bobrik. A former domestique Alberto Volpi and Ferrari disciple won the former British World Cup race that season but later tested positive. That winter Polini was fired with Ferrari taking full responsibility for all riders. Polini revealed in an interview of doping products that could get through the controls including EPO.
Mecair evolved into Gewiss in 94 in which they had that remarkable season with the now infamous 1-2-3 in Fleche Wallone. Berzin had a decent debut season but no major results but once he started working with Ferrari, in just his second season as a pro he won the Giro. Gewiss would dominate the 94-95 seasons. Piotr Ugrumov who had been a pro with SEUR in Spain for a few seasons was a rider without any outstanding results but suddenly became a major Tour contender with Mecair/Gewiss.
There are just too many sudden improvements in riders performances to put it down to improved training or unfulfilled potential. I dont think there is any doubt that EPO could turn a useless rider into a decent one and a decent rider into a top rider. David Millar was never at the level of an early career Lance so thats like comparing apples and oranges. There is also the factor of how different riders respond to EPO and how far they are prepared to jack .
Remember Riis jacked to 60% haematocrit whilst Festina stayed around 50% according to Willy Voet, Festina then had a great Tour in 97 when the 50% limit was brought in and the other guys couldnt jack so high. That is why it levelled the playing field slightly and Riis came back down to earth but if people think Ullrich was clean in 97, they are clueless.
Of course EPO or other drugs are not the sole reason for creating a Tour winner but they still play a significant part. It could be the difference between the most talented guy finishing 1st or top 10 and that is a significant difference.
Millar was never a Tour riders but his performances definitely improved whilst he was on EPO. Millar never was top 50/60 in a GT tour before he took EPO so I dont see the point of focusing solely on Millar. He improved on EPO and since his comeback, has been nowhere near the same rider, explaing that one away.