These are good points @Madollar and Kusadikika. Some record attempts do benefit from someone pushing you, especially if the hares fail. But you look at that change from 30-35K. A serious record attempter must control the race from here or else he fails, no matter who else is in the mix.
This is where the value of fitness fades and mental attitude becomes all important. GEB had mental strength in spades. So did Wanjiru but he never seriously attempted the record.
Bekele has pace, no question. But the evolution of Marathon record attempts is no longer speed but even splits. A metronomic pace that deliberately conserves energy in the first half in order to repeat the same in the second half.
Then you pray for the gods of marathon running to be in a good mood that day.
"The opposite of a correct statement is a false statement. But the opposite of a profound truth may well be another profound truth." (Niels Bohr)