Measurements we ran ourselves and industry claims we traced to their sources: site migrations, redesigns, AI crawlers, and everything else that quietly changes the web. Written for SEO professionals who are tired of statistics nobody can footnote.
We read robots.txt on the web's most-visited domains and found that sites block model-training crawlers several times more often than the AI-search crawlers that send readers back. Then we found that most of that gap was never a decision.
The most-quoted statistic in migration SEO, traced back through every citation we could find. What the evidence actually supports, and the honest numbers to use instead.