Disclaimer: I work for Google and am an interviewer. I'm speaking for myself and not my employer, and not citing any internal data, just my own experience.
I don't know what our offer rate is, but I think it is probably well below 50% even once you make it onsite, so being above average wouldn't be enough.
Our hiring process is also tuned for low false positive rate, at the cost of high false negative rate. Maybe it's optimal, I don't know, but two of my referrals ended up going to Facebook after not getting offers at Google, and doing very well there (one exceptionally so). We definitely should have hired them and we didn't.
I don't know what our offer rate is, but I think it is probably well below 50% even once you make it onsite, so being above average wouldn't be enough.
Our hiring process is also tuned for low false positive rate, at the cost of high false negative rate. Maybe it's optimal, I don't know, but two of my referrals ended up going to Facebook after not getting offers at Google, and doing very well there (one exceptionally so). We definitely should have hired them and we didn't.