I have never, repeat never, had a site penalized that had a 100% relevant tier one of backlinks. Google bases "relevancy" on these three things.
First of all, backlinks to your domain or specific web pages are important. The more inbound links you have, the higher your overall Google Page Rank, right?.
By means of the interface, the tool accesses the backlink databank of Backlinks still count as the most important ranking factors for Google.