Again I think two factors are heavily causing this, people who are cousins

1) Who haven't mapped their tree to your actual shared ancestor, so it does it's best guessed on the group of people who match

2) Who have names/dates it hasn't consolidated as the same ancestor, and the same result

In the original blog post about this they suggested they tried to map up to people who you didn't already have a shared ancestor for, so either I misunderstood, that's broken, or the above 2 reasons are causing these odd results that actually make sense from the fact the system can only do so much.

If there was a easier way to get people to normalize/link ancestor names/dates it would probably heavily improve this system.