There’s no disclosed Google tool that definitively labels which mechanism caused a specific ranking, so this is inferential diagnosis based on ranking and content patterns, not a confirmed attribution method. That said, there are several concrete signals worth checking, and taken together they give a reasonably confident read on which mechanism is more likely doing the work.
Mechanism: what passage ranking actually is, and why the distinction matters
Google confirmed passage ranking (sometimes referred to as passage indexing in press coverage) in its 2020 announcement describing a system that can identify and rank individual passages or sections within a longer page as relevant to a specific, narrow query, even when the page’s overall subject isn’t primarily about that narrow topic. The practical effect is that a comprehensive page covering many subtopics can surface for a very specific query addressed in just one section, without the whole page needing to be about that specific thing.
Topical authority, by contrast, describes a page (or domain) ranking well across a broad set of related queries because Google’s systems have learned to associate that page or domain with strong, comprehensive coverage and trust signals in that topical area generally. A page can rank for a niche sub-topic query because Google’s passage-level matching pulled out one specific relevant section, or because the page (or its domain) already carries broad authority in that subject area and would likely rank reasonably well across many related queries, not just the one narrow one.
Diagnostic signals to check
Does the ranking query map to one narrow section, or does it reflect the page’s overall theme? If the query terms correspond to a specific paragraph or subsection that’s a small part of a much broader page, and that subsection isn’t representative of what the page is mainly about, that’s a passage-ranking-consistent pattern. If the query terms align with the page’s central theme, expressed throughout the content, that’s more consistent with general topical relevance matching, not a passage-specific mechanism.
Does the domain or page have broader topical authority in that specific niche, or just this one page addressing it in passing? Check whether the domain ranks well across a range of related queries in that sub-topic’s specific area, not just the one query in question. If the domain has no other presence in that niche, no other content addressing related angles, no apparent topical depth there, and yet ranks for this one specific niche query via one section of an otherwise differently-focused page, passage ranking is the more plausible driver, since there’s no broader authority signal to otherwise explain the ranking.
Does Google’s snippet or highlighted result pull from a specific section rather than the page’s introduction or title? When Google displays a search result with a highlighted or bolded snippet pulled from deep within the page (particularly visible when Google shows the passage-level snippet with jump-to-section behavior in the SERP), that’s a reasonably direct signal that Google’s system identified that specific passage as the relevant match, consistent with passage ranking being the active mechanism for that query.
Does the page rank well for many queries sharing vocabulary with its overall content, or narrowly for isolated niche terms scattered across different sections? A page that ranks broadly across queries reflecting its dominant theme is showing topical-authority-driven ranking behavior. A page ranking for a scattered set of narrow, specific queries that each map to a different isolated section, with no clear pattern tying them to the page’s main theme, is more consistent with passage-level matching operating independently across multiple parts of the same document.
A hypothetical illustration
Imagine a hypothetical site, “Example Gardening,” with one long comprehensive guide to houseplant care that includes a short section on a specific rare succulent. Hypothetically, if that page ranked for the narrow query about that succulent, but the domain had no other content addressing succulents specifically and no other rankings in that niche, while Google’s SERP snippet for the query pulled directly from that one subsection rather than the page’s introduction, that combination would point toward passage ranking as the likely mechanism, not general topical authority in succulent care.
Practical implication: this changes what “more of the same” actually improves
The reason this diagnosis matters practically is that the two mechanisms respond differently to further optimization. If topical authority is the driver, building out more comprehensive, interlinked content across the broader subject area is likely to reinforce and expand that ranking strength. If passage ranking is the driver for a specific niche query, the page’s overall topical breadth is largely irrelevant to that particular ranking, what matters is whether that specific section remains a clear, well-structured, directly relevant answer to that narrow query, and improving unrelated parts of the page won’t move that specific ranking one way or the other.
Practitioners should treat this as directional inference from observable patterns, not a certainty. The honest framing is that some niche rankings likely reflect a mix of both mechanisms working together, a domain with some topical authority and a page with a well-matched passage will often outperform either signal alone, and Google doesn’t expose enough granularity to cleanly separate the two in every case.
