Fortunately, Google does not rank pages based on PR, nor age of the domain. This is a point that many folks have trouble understanding. Google is trying to return the best search results possible, so from the user’s point of view, relevance is always the most important factor.
Google treats relevance as the primary factor and other things like age and PR are used to weigh the value of backlinks. Backlinks play an important role, but it’s never been just about the number of backlinks. It’s how backlinks influence relevancy that is important.
When analyzing your competition you need to focus on signals of relevancy and the strength of those signals. A page could be 10 years old with hundreds of thousands of backlinks and a PR10 and yet not be serious competition. That’s because none of those factors specifically pertain to relevancy. If the page is barely relevant to your target keyword, and the backlinks have little or no relevance, then that page will be very easy to outrank.
What makes a page hard to outrank are aged signals of relevancy. The PR of the page you are trying to outrank is not a reliable indicator of strength. You need to isolate the backlinks that are highly relevant and determine the strength of those inbound links by looking at the PR and age of those inbound links. Look only at the relevant backlinks, ignore all others as they have no influence on ranking for your targeted keyword.
And finally, remember that search engines rank individual pages, not websites. Focus on the ranking factors for the individual page, not the website. They rank based on relevancy, so isolate and look strictly at the strength of the signals that are relevant and you will be able to judge the true strength of competition.
The problem with most SEO tools is they do not isolate the pertinent signals. Instead, they lump the irrelevant in with the relevant signals which seriously limits their usefulness.