I gave the program in 2011-2012 to the teacher of Geoffrey, Charles Ngeno, when Kirui ran 26'55" in 10000m. After Abel Kirui won Chicago in 2016, Geoffrey Kirui started to train with me directly, coming from Keringet to Iten several time, and I went from Iten to Keringet many times. During this period, Piet continued to take care of Geoffrey, following him when we were not together, according to my plan. This collaboration lasted till World Championships, including the victory in Boston 2017, when in Boston I clearly said, during an interview, that Geoffrey was one of the best talents for marathon, but, because his "low mileage" (160 km per week), NEVER could reach his potential (something that clearly happened).
And about Asbel, you show one time more that don't know anything about what happened.
Asbel never was with me. On 31 May 2017, in Eugene, Ronald Kwemoi won the Prefontaine Mile, and Asbel was the last in the race. Immediately after the race, he sent me a message asking to help him. We seated together discussing his situation, and I told him : "You are an aerobical animal, you are not Rudisha. You won WJCh in Cross Country in 2007 in Mombasa on the distance of 8 km. But if the Asbel 2007 meets the Asbel 2017 in a race of 8 km, gives him 3 minutes, so you lost ALL your aerobical power, and if you want to go back at the top, need to rebuild that quality". I gave him one week of training for checking his mental attitude, in this week there was a workout of 8 km at 3'06" in 24'48". The next day he wrote me : "I was not able to run in 24'48". The training was too much demanding. I ran 25'36" (that is 3'12" pace) and was not able to sleep well in the night because I was too tired". After this, I never gave him any other program, and never followed him in training.
A workout like this (8 km at 3'06") is an example of "Tempo", very slow for an athlete of the level of Asbel, if well trained. In Kenya, there are not less than 30-40 athletes able running in training 8 km at 3'12", like Asbel did, and the maintenance of a good level of Aerobic Power is important also for runners of 1500m, especially if are of "Aerobic" typology.
When Silas Kiplagat came to me, hisd last race was a road race of 10 km in 28' flat (he was in training together with Kitwara). But he liked 1500m and track. In 4 months, in his first competition in Europe (Monaco meeting) in 2010, he won running 3'29"27, and till when accepted to do in his training long and fast "Tempo" from 6 to 12 km, ran 4 times under 3'30", and was competitive at maximum level till 2015. When he left the group, because was no more the "star" of the camp due to the improvement of Ronald Kwemoi, started to look for speed and totally cancelled any "Tempo". In a session during February 2017, Ronald ran 10 km in 29'06", and Silas 31'20". Also if still young, with that new mentality never was able to come back.