How do you measure the business impact of technical SEO?

Technical change → search-engine behavior → visibility → organic traffic → conversions → revenue/leads

For example, improving internal linking should not be reported only as "2,000 more internal links." The useful question is whether important URLs became more discoverable and subsequently gained impressions, clicks or business outcomes.

Useful metrics can include:

• indexed important URLs;
• crawl distribution;
• organic impressions;
• organic clicks;
• non-brand visibility;
• organic leads;
• organic revenue;
• page-level conversion rate.

Do not treat technical metrics as guaranteed ranking metrics. Google explicitly notes that meeting technical requirements does not guarantee crawling, indexing or serving.