So...you had a hunch all along? Chepchirchir is a smoker; 2:19:47 - puts her as the 9th fastest Kenyan female all time.
You can refer to previous explanations, because there is no need for me to change any.
Athletes take drugs based on belief and hope. Sometimes it works. Sometimes they get busted.
Belief in drugs in the hope of improved performance is deep and wide -- for many examples, just visit letsrun forums.
Given the circumstances around Sumgong, Chepchirchir's suspension was predictable.
Renato explained in the very first post how the lack of central management makes it hard to control athletes, and protect them from outside influences, when they are not at the training camp.