Off-Page SEO 2026: From PageRank to Entity Authority
Off-page SEO has fundamentally shifted in 2025-2026: brand mentions correlate at 0.664 with AI visibility, backlinks only at 0.218. The Google API leak confirmed a site-wide authority score (siteAuthority) and the NavBoost system based on 13 months of click data. Share of Model (SoM) is the new KPI.
Key Takeaways
- ✓Brand Mentions correlate 3x stronger with AI visibility than backlinks (0.664 vs 0.218)
- ✓Google API Leak confirmed siteAuthority and NavBoost (84 mentions in docs)
- ✓NavBoost uses 13 months of click data: goodClicks, badClicks, lastLongestClicks
- ✓Gary Illyes: "Links are important, but people overestimate their significance"
- ✓Share of Model (SoM) is the new KPI — probabilistic, not deterministic
- ✓40-60% of cited sources change monthly across AI platforms
- ✓Only 11% of domains are cited by both ChatGPT AND Perplexity
Google's off-page evaluation model has undergone its most fundamental transformation since the company's founding.
The API Leak and NavBoost
The 2024 Google Content Warehouse API Leak — over 2,500 pages of internal documentation with 14,000+ attributes — confirmed: Google operates a site-wide authority signal (internally called "siteAuthority"), relies heavily on click-based re-ranking through the NavBoost system (mentioned 84 times in the leaked documents, confirmed by VP Pandu Nayak in the DOJ proceedings), and considers brand mentions even without backlinks as trust signals.
NavBoost uses a rolling 13-month window of aggregated click data: goodClicks (positive engagement), badClicks (pogo-sticking), and lastLongestClicks (the last result where users dwell the longest). Even if a page has excellent backlinks — poor user engagement will demote it.
AI Platforms Evaluate Authority Differently
Each platform has its own trust signals: Google AI Overviews prioritizes traditional SEO plus Entity Authority (Reddit 21% of citations). ChatGPT trusts the Bing index and training data consensus (Wikipedia 47.9%). Perplexity trusts experts and reviews (Reddit 46.7%). Gemini trusts structured brand content (52.15% of citations from brand websites).
Share of Model as New KPI
Share of Model measures how frequently a brand appears in AI answers. It is probabilistic: Less than 1 in 100 chance that ChatGPT delivers the same brand list. 40-60 percent of cited sources change monthly. This requires continuous monitoring and sustainable brand building instead of one-time campaigns.
Data & Statistics
Brand Web Mentions: r=0,664 Korrelation mit AI-Sichtbarkeit
Ahrefs 75K-Brand-Studie (2025)Backlinks: r=0,218 Korrelation — 3x schwächer als Brand Mentions
Ahrefs 75K-Brand-Studie (2025)NavBoost wird 84-mal in den geleakten Google-Dokumenten erwähnt
Google Content Warehouse API Leak (2024)45,7% aller Google-Suchen nach Volumen sind Markensuchen
Ahrefs (2025)“Off-page SEO in 2026 is less about acquiring links and more about building a brand that people naturally talk about and reference.”
— Rand Fishkin, CEO SparkToro, Co-Founder Moz