Again, the number of people not knowing anything about athletics, but fanatic of doping, continues to grow. The mother of idiots always is pregnant.
The explanation of the controperformance of Kenyans is very simple : they continue to train in the same way for every marathon, not considering the different situations they can face in the race.
They train hard, and in many cases well, but one thing never change : the time of their training. So, long runs at 6 in the morning, and normally good training in comfortable situation as weather.
They came Beijing 4 days before, from a situation of 12 degrees in training, and found a situation of 30-33 degrees, with 90% of humidity.
The same happened in Osaka 2007. The first two athletes (Luke Kibet 2:15'59" and Mubarak Shami (Richard Yatich) in 2:17'21") were in training with me and we went more than 10 times from Iten (2400m) in the valley at 1000m of altitude, for running specific long runs and specific marathon speed endurance workouts at 11 o'clock, when the temperature was around 32 degrees. All the other Kenyans, training in "classic" way, were not able to finish, apart William Kiplagat in 2:19'.\
When I read in a Kenyan newspaper the interview of the head coach Julius Kirwa about the two marathon teams ("we decided to prepare in Iten because the weather is almost the same") I immediately understood Kenyan could not be competitive in this situation, since I lived in Iten long time, now I'm the responsible of China, and well know the weather conditions in Iten and Beijing are exactly the opposite....
About the participation of the athletes, frankly I don't understand why Wilson Kipsang and Dennis Kimetto wanted to run WCh. If you are the number one in the world (Kipsang, in spite of his defeat by Kipchoge in London is without any doubt the most consistant marathon runner during the last 4 years) or the WR holder, winning WCh doesn't add anything to your valour in the market, but losing the race can, on the contrary, reduce the appearance fees you receive in the Majors.
So, because they were both in competition, and in any case it was not possible to have to winners, one of the two of sure had to lose the race, and I don't understand the reason.
Other consideration : for personal experience, NEVER we saw athletes running London at their best, to be in shape for the World Championships or Olympic Games in August. In 2012, I was the one following the preparation of Wilson Kipsang dominator of London, and together the coach Gabriele Nicola the preparation of Mary Keitany, who seemed unbeatable. We can't blame AK, because in this case we had full support and could decide what we had to do, without any interference.
Also using the maximum of professionalism, both from our side as coaches and from the side of the athletes, we were not able to recover the same shape of London.
In Olympic, the winners were Stephen Kiprotich, who ran his marathon in February, and Tiki Gelana, who ran in Rotterdam withou any nervous tension, because the second (Valeria Straneo) was 5 minutes behind.
What is difficult to recover is not the body efficiency, but the full concentration depending from the nervous system.
So, their defaillance has nothing to do with doping, but with two other reasons : mistakes in the selection (because if you want somebody competitive in WCh or Olympics you need to give a deadline inside half of March, possibly running a marathon of not top level), and mistakes in the preparation.
Remember that the athletes mostly suffering hunid conditions are the ones living and training in altitude, because the weather is always dry, and humidity affects the breathing in different way if there is adaptation or not.