The first American in history to break 13 is BK. And he does so after training with several people whose cleanliness is questionable.
Then we go through the dark ages. In 2003, Jorge Torres was the only American in the 5k at the world championships, and that was because he was the ONE runner with the B standard. In 2004 there was a documentary made about the travails of chasing the Olympic 5k A standard, and I don't think anyone hit it. In 2008, Fam led a LAP in the steeple at the Olympics and we were just so excited.
Then, out of nowhere, the floodgates open. We have a top ranked steepler. We have a slew of runners under 13:05. Olympic and world championships medalists. And they primarily come from two groups.
How could you possibly believe that ONE group achieving similar results (that were previously unobtainable) is doped, while the other one is clean?
Both of those groups are clean, or they're both dirty.