I haven't worked at Google, but from what I've heard, politics becomes an even bigger issue. If you're only worried about your boss (and your boss's boss, presumably), that's like two people to impress. If you're going to get graded by a committee, not only do you have to do good work, you also have to make sure everybody on the committee knows you're doing good work; and you have to fight people on your team to get the opportunities to do visible good works.