Even clinging to the once towering bridge, the only thing Kayce could see was desert. Yesterday, San Francisco hummed with life, but now there was nothing but the hot hiss of the wind. Google’s Mobilegeddon blew out from Mountain View like Death’s last exhale, and for the first time since she regained consciousness, Kayce wondered if she was the last SEO left alive.

We have a penchant for melodrama, and the blogosphere loves a conspiracy, but after weeks of speculation bordering on hysteria, it’s time to see what the data has to say about Google’s Mobile Update. If you've been following MozCast, you may be unimpressed with this particular apocalypse:

The purple bars all occurred after the pre-announced roll-out date (April 21st). Temperatures hit 66.1°F on the first official day of Google's Mobile Update (the system is tuned to an average of 70°F), and stayed low until April 24th. The problem is that this system only measures desktop temperatures, and as we know, Google's Mobile Update should only impact mobile SERPs. So, we decided to build a MozCast Mobile, that would separately track mobile SERPs (Android, specifically) across the same 10K keyword set. Here's what we saw for the past 10 days on MozCast Mobile:

Across the board, mobile temperatures run a little hotter (which could just be quirks in how we measure). On April 21st, mobile temps were slightly higher, but nothing to write home about. So far, Day 2 (April 22nd) has shown the hottest temperatures, hitting 79.8°F. Interestingly, the difference between desktop and mobile flux was almost 18° on Day 2. There's another small spike on April 24th, but as you an see from the first graph, that spike also impacted desktop rankings. Whatever happened that day doesn't appear to be related to any kind of mobile algorithm update.

Since building MozCast Mobile, we've also been tracking how many page-1 URLs show the "Mobile-friendly" tag. Presumably, if mobile-friendly results are rewarded, we'd expect that number to jump and then stay higher. Here's that stat back to April 18th:

Even before April 21st, a surprisingly high number of the URLs we track carried the "Mobile-friendly" tag. We don't have a lot of historical data, but the low point was around 66.3% (on April 8th). That number has steadily crept up since then, but it's unclear whether this is an algorithmic change, data being updated by Google, or sites being updated last-minute to be more mobile friendly. Please note that the Y-axis on this graph is restricted (50-75%) to help better visualize the gradual increase over time.

On April 22nd, the number of sites with "Mobile-friendly" tagging bumped up to 72.3%, and it's crept up slightly since then (currently at 72.8%). Again, we can't really determine the cause for this increase, but, one way or another, Google seems to be getting what they wanted

Tracking a long roll-out

Although Google has repeatedly cited April 21st, they've also said that this update could take days or weeks. If an update is spread out over weeks, can we accurately measure the flux? The short answer is: not very well. We can measure flux over any time-span, but search results naturally change over time – we have no real guidance to tell us what's normal over longer periods.

The "Mobile-friendly" tag tracking is one solution – this should gradually increase – but there's another metric we can look at. If mobile results continue to diverge from desktop results, then the same-day flux between the two sets of results should increase. In other words, mobile results should get increasingly different from desktop results with each day of the roll-out. Here's what that cross-flux looks like:

I'm using raw flux data here, since the temperature conversion isn't calibrated to this data. This comparison is tricky, because many sites use different URLs for mobile vs. desktop. I've stripped out the obvious cases ("m." and "mobile." sub-domains), but that still leaves a lot of variants.

Although April 21st was quiet, we did see a decent bump around Day 2 (April 22nd), which matches our other data. This divergence has continued, but not dramatically. It appears something did change around April 22nd, but the impact isn't what any of us probably expected.

Tracking potential losers

No major sites are reporting hits yet, but by looking at the "Mobile-friendly" tag for the top domains in MozCast Mobile, we can start to piece together who might get hit by the update. Here are the top 20 domains (in our 10K data set) as of April 21st, along with the percent of their ranking URLs that are tagged as mobile-friendly:

1. en.m.wikipedia.org — 96.3%
2. www.amazon.com — 62.3%
3. m.facebook.com — 100.0%
4. m.yelp.com — 99.9%
5. m.youtube.com — 27.8%
6. twitter.com — 99.8%
7. www.tripadvisor.com — 92.5%
8. www.m.webmd.com — 100.0%
9. mobile.walmart.com — 99.5%
10. www.pinterest.com — 97.5%
11. www.foodnetwork.com — 69.9%
12. www.ebay.com — 97.7%
13. www.mayoclinic.org — 100.0%
14. m.allrecipes.com — 97.1%
15. m.medlineplus.gov — 100.0%
16. www.bestbuy.com — 90.2%
17. www.overstock.com — 98.6%
18. m.target.com — 41.4%
19. www.zillow.com — 99.6%
20. www.irs.gov — 0.0%

I've bolded any site under 75% – the IRS is our big Top 20 trouble spot, although don't expect IRS.gov to stop ranking at tax-time soon. Interestingly, YouTube's mobile site only shows as mobile-friendly about a quarter of the time in our data set – this will be a key case to watch. Note that Google could consider a site mobile-friendly without showing the "Mobile-friendly" tag, but it's the simplest/best proxy we have right now.

As of April 28th, there was no major movement in the top 20, with the exception of some immediate position swaps (ex. #7 with #8), but these are fairly common. YouTube actually gained SERP share slightly (although it's still in #5 in our data). The IRS did fall a couple of positions (to #23), but tax season is also drawing to a close, and movement beyond the top 20 is pretty common.

Changes beyond rankings

It's important to note that, in many ways, mobile SERPs are already different from desktop SERPs. The most striking difference is design, but that's not the only change. For examples, Google recently announced that they would be dropping domains in mobile display URLs. Here's a sample mobile result from my recent post:

Notice the display URL, which starts with the brand name ("Moz") instead of our domain name. That's followed by a breadcrumb-style URL that uses part of the page name. Expect this to spread, and possibly even hit desktop results in the future.

While Google has said that vertical results wouldn't change with the April 21st update, that statement is a bit misleading when it comes to local results. Google already uses different styles of local pack results for mobile, and those pack results appear in different proportions. For example, here's a local "snack pack" on mobile (Android):

Snack packs appear in only 1.5% of the local rankings we track for MozCast Desktop, but they're nearly 4X as prevalent (6.0%) on MozCast Mobile (for the same keywords and locations). As these new packs become more prevalent, they take away other styles of packs, and create new user behavior. So, to say local is the same just because the core algorithm may be the same is misleading at best.

Finally, mobile adds entirely new entities, like app packs on Android (from a search for "jobs"):

These app packs appear on a full 8.4% of the mobile SERPs we're tracking, including many high-volume keywords. As I noted in my recent post, these app packs also consume page-1 organic slots.

A bit of good news

If you're worried that you may be too late to the mobile game, it appears there is some good news. Google will most likely reprocess new mobile-friendly pages quickly. Just this past few days, Moz redesigned our blog to be mobile friendly. In less than 24 hours, some of our main blog pages were already showing the "Mobile-friendly" tag:

However big this update ultimately ends up being, Google's push toward mobile-first design and their clear public stance on this issue strongly signal that mobile-friendly sites are going to have an advantage over time.

One other bit of good news: we are actively exploring mobile rank-tracking for Moz Analytics. More details are in this Q&A from MA's Product Manager, Jon White.

Stay tuned to this post (same URL) for the next week or two - I'll be updating charts and data as the Mobile Update continues to roll out. If the update really does take days or weeks, we'll do our best to measure the long-term impact and keep you informed.