One thing I've always wondered is if every search company looks better than their competitors on their own metrics. Seems totally plausible given how many different ways there are to define metrics, and how different the types of queries that each search engine receives might be.

Sometimes you know you're getting a beatdown and your metrics reflect it. Your goal is to simply close the distance over time.

But one thing that happens is that if you decide a metric is important and make it a KPI, you are then trying to implement features based on their ability to "move the needle" on that KPI. So if you are effective at meeting goals, you tend to improve on that KPI (the one you are testing for improvement on) more than you do on some other metric that you are not measuring your performance against.

So yes, if different competitors are using different metrics, they're likely to each perform the best on their own metrics.

One interesting fact from their study though was that results returned with the Google logo was perceived as better, even if it came from Bing. This is unfortunately why marketing is such a big deal.