You only have to look at the improvements he made over such a period of time, linked directly to him moving to the Oregon Project and very close association with Salazar. Obviously we'll never know, for sure.
Reminds me of the brilliantly funny Mike Parry with his forecast and ways of improving sport. He was sure ( tongue in cheek ) that we would see a 1 second 100metres…. perhaps he was right ??!! He also suggested that racehorses had wing mirrors to benefit jockeys moving out of position.
But then at the peak of his career London 2012 he was still around half a minute off the world record. You'd think if he was doping he could get closer to it or break it. People look at long term world records and wonder about how clean someone is because with modern technology, diets etc you'd think they would get beaten. We wouldn't think Jonathan Edwards was doing though despite nobody getting near his world record.
You could pump me up with any drugs on the face of the planet and I'd be hours behind the record I reckon... So It's not a great piece of evidence