Algorithm Update or Site Issue? How to Tell Fast

A client messages you on a Tuesday morning: "Traffic is down 30%. Is this an algorithm update?" The honest answer, before you investigate, is that you have no idea. And guessing wrong is expensive in both directions — you either spend three weeks rewriting content when the real problem was a staging robots.txt pushed to production, or you file a support ticket about a broken plugin while a core update quietly reprices your entire category.

Here is the practical way to separate an algorithm update or site issue in under an hour, with the specific signals that distinguish them.

The short answer

Algorithm updates are gradual, sitewide, category-wide, and dated. Site issues are sudden, scoped, and unique to you. If your drop started on one specific day, affects one folder or template, and your competitors in the same SERPs didn't move, it is your site. If it bled out over 5 to 10 days, touched most of the site unevenly, and three competitors swapped positions in the same window, it is the algorithm.

Everything below is how you confirm which one you're looking at instead of assuming.

Three checks that resolve 80% of cases

1. Shape of the curve: cliff or slope?

Open Search Console, set the date range to the last 3 months, and look at clicks and impressions together. You are looking for the shape, not the number.

• A cliff — traffic drops 40% between Tuesday and Wednesday and stays flat at the new level — is nearly always technical or manual. Something changed on your end, or a penalty landed.
• A slope — a staggered decline across 5 to 14 days, sometimes with a partial bounce mid-way — matches how core updates roll out. Google processes the update in waves, and your site gets re-scored at different times for different query clusters.
• A step-down with impressions flat — clicks fall but impressions hold — means you're still ranking but losing the click. That points to SERP layout changes (AI Overviews, a new featured snippet, more ads) rather than a ranking loss. We've written about why traffic drops when rankings don't in more detail.

2. Scope: is it everything, or one slice?

In Search Console, compare the 28 days before the drop to the 28 days after, then break it down by page. Sort by click difference. Now ask: is the loss spread proportionally across 400 URLs, or is 85% of it coming from 12 URLs that share a folder, template, or intent type?

Concentrated loss means something specific broke. A blog that lost traffic while product pages held steady is a content or indexing problem on the blog. A site where every URL lost 15 to 25% evenly is a sitewide re-evaluation — either an algorithm update or something sitewide like a Core Web Vitals collapse or a domain-level issue.

Run the same breakdown by query. Updates tend to hit query types — informational queries get reshuffled while transactional ones don't, or vice versa. Site issues hit URLs regardless of query intent.

3. Competitors: did the SERP move, or just you?

This is the single most decisive check and the one most agencies skip. Take 10 representative keywords where you lost positions. Look at who occupies positions 1 through 10 now versus a month ago.

If three or four new domains entered the top 10 and the old leaders slid down — the SERP itself got rewritten. That's an update. If the SERP looks almost identical except your URL moved from 4 to 19 and everything below you shifted up one, you got demoted alone. Nothing about an algorithm update singles out one site in an otherwise-stable top 10.

Signals that point to an algorithm update

• The start date matches a confirmed rollout window. Check Google's Search Status Dashboard, not just Twitter chatter.
• Multiple clients in your portfolio moved in the same 72 hours — especially in the same vertical. If you manage 20 sites and six wobbled at once, that's not six coincidental technical failures.
• Ranking changes are directional but messy: some pages up, more pages down, nothing at zero.
• Nothing in your deployment log, CMS revision history, or link profile changed in the two weeks before.
• Indexing is healthy — pages are still indexed, still crawled, still showing impressions. They're just ranking lower.

That last point matters. Updates change where you rank. They rarely remove pages from the index entirely. If URLs disappeared from Search Console's indexed count, stop looking at algorithm news.

Signals that point to a problem on your site

Self-inflicted technical wounds

In order of how often they actually cause the panic call:

1. A noindex tag shipped to production. Usually from a staging environment or a WordPress "Discourage search engines" checkbox. Check the Page Indexing report for a spike in "Excluded by noindex."
2. robots.txt change. One stray Disallow: / or a blocked /blog/ directory. Check the robots.txt report and the file's last-modified date.
3. A site migration or redesign where URLs changed and redirects were partial. Look for 404s in the Page Indexing report rising in the same week.
4. Canonical tags pointing somewhere wrong after a plugin update — often all canonicals resolving to the homepage.
5. Server instability or slow TTFB during a crawl spike. Check the Crawl Stats report for a rise in 5xx responses.
6. Lost links — a partner site redesigned and dropped 40 referring links, or a paid placement expired.
7. Manual action. Rare, but check the Manual Actions tab in 10 seconds before theorizing.

There's a longer breakdown of these in our guide to why Google rankings drop and the nine causes to check, but the triage order above is what we'd run first.

Measurement artifacts that aren't real drops

Before you diagnose anything, confirm the drop is real. A surprising share of "traffic collapsed" tickets are:

• GA4 tag removed during a site update — Search Console will show flat clicks while GA4 shows a cliff. That mismatch is diagnostic in itself.
• A new consent banner defaulting to deny, cutting measured sessions by 20 to 40% overnight with zero actual traffic change.
• Bot traffic being filtered out after a Cloudflare rule change — which is a reporting improvement, not a loss.
• Seasonality. A B2B site always dips the last two weeks of December. Compare year over year, not month over month.

Rule of thumb: if Search Console clicks are stable and only analytics dropped, it's a tracking problem. Search Console is measured on Google's side and doesn't care about your tags.

Reconstruct the timeline before you theorize

The fastest diagnostician is the one with a change log. Pull every change made to the site in the 21 days before the drop — deploys, plugin updates, content edits, hosting changes, theme updates, new redirects, DNS changes, anything the client's web team touched without telling you.

Most agencies can't do this because the record lives in four places: someone's Slack DMs, a Trello card, the dev's Git history, and a verbal agreement in a Zoom call. Keeping client work, deploy notes and content changes in one system — which is part of what PeakKR is built for — turns a