I've heard the argument about the small track plenty of times before.
There are folks who make this argument whenever anybody runs fast.
However, given that blazing fast marks were posted at not just one but two different National Games, 1993 and 1997, at different venues, I think it we can rule out being mismarked.
Besides, we've already seen that the marks are not outside the realm of human achievement as we all once thought them to be. The 1500 and 10000 have both fallen, and no one has taken a serious crack at the 3000.
Ma Junren was a brutal coach who controlled every aspect of his athlete's lives. It was like the military. He ran them at punishing mileages at high altitude in Tibet. He admitted to beating them.
I do wonder why the IAAF has not come out with anything since saying that they would first try and authenticate the letter. This story broke in february. Does it really take 8 months to find out if the letter is genuine?