Google actually had to dial down the bonuses circa 2011. For one thing, to keep the comp looking competitive, it makes sense to have a larger component, because

Google actually had to dial down the bonuses circa 2011. For one thing, to keep the comp looking competitive, it makes sense to have a larger component, because until this rebalancing bases were unimpressive there. For another too large a bonus creates more competition than one would like in the engineering discipline, where the overall success depends on people working well together. So they just cut the bonus in half and added it to the base.