Easy to blame the VSC
But as Hamilton closed up on Vettel he had to back off.
Why? Mercedes designed a car that would be in the lead all the time with maximum undisturbed air flow. That didn't happen in Australia, so when Hamilton got close to Vettel his engine and other components started to overheat, meaning his engineer ordering him to back off to cool every thing down. To my knowledge the same thing occurred to Bottas who struggled in the midfield, which is uncharacteristic of him.
Biting the hand that feeds IT
