Then let's keep it at people he beat on the track. Why do pple he beat on the track like Geoffrey Kamworor and Bedan Karoki beat him resoundingly at half marathon?
You are asking why did not Mohammed Farah stick to the track and race his best event. Farah knew the truth: Farah could not sprint final 300m in a 1500m race well against elite 1500m runners. Sans pacers, in Olympics and World Championships Farah knew most likely 5000m & 10000m races would not be near world record pace. One's ability to thrive while in anaerobic state diminishes as one gets older. Farah knows at his age, 36 it is too difficult to train to kick in 5000m & 10000m races. It is no shame that Farah is not one of all time greats at Marathon. His personal bests 1500m through Marathon are very impressive.