The document discusses how link building metrics are often measured incorrectly by focusing too much on domain-level metrics like domain authority rather than page-level metrics or actual outcomes. It recommends focusing on the underlying mechanism of PageRank by considering the quality and number of incoming links, measuring links in phases from initial prospects to long-term outcomes, and prioritizing concrete metrics like referral traffic and rankings over domain-level proxies. This will provide a more accurate picture of how individual links contribute to search performance.