The claim
Not all links pass equal value; a link's contribution depends on its prominence, position and likelihood of being clicked.
What the evidence shows
The Reasonable Surfer patent models a user who follows some links more than others, so a prominent in-content link carries more weight than a boilerplate footer link. This refines the original random-surfer PageRank model and supports the practice of positioning important internal and external links where users are genuinely likely to engage.