In London he kicked well off of a slow pace. In the other WCs the pace over the last 2+ miles is like low 13 min 5000 meter pace. He almost never has a kick off of that pace and always loses a step when the kicking starts. He even lost a few steps in London before he came back.
Also, his London accomplishment was awesome but there was some good fortune. He had a race in which both Ethiopia and Kenya had competitors who could not kick well anymore. Ethiopia had GG (fell off pace) and the Bekele - who could not close below 56 anymore.
Kenya had (1) Bedan Muchiri, who only kicked well once, (2) Kiprop (hurt) and (3) Masai - not a great kicker as far as I recall.