Tom Capper Mozcon 2021 - Core Web Vitals - The Fast & The Spurious

The Fast & The
Spurious
Core Web Vitals & SEO
Tom Capper
Search Scientist, Moz
@THCapper

@THCapper
You can’t afford to call…

@THCapper
Agenda:
The flaws of CWV
What’s taking so long?
Does it matter?
What to do next

@THCapper
https://developers.google.com/search/blog/2020/11/timing-for-page-experience

@THCapper
Largest Contentful Paint

@THCapper
Remove
links
Harder to
click

@THCapper
Remove
links
Harder to
click
First input
bait

@THCapper
Cumulative Layout Shift

@THCapper
The CrUX of the matter

@THCapper
The CRuX of the matter
… we can employ techniques like grouping pages
that are similar and compute scores based on that
aggregation …
- https://support.google.com/webmasters/thread/104436075?hl=en

@THCapper
What's taking so long?

@THCapper
May 2020: It’ll be in 2021
https://developers.google.com/search/blog/2020/05/evaluating-page-experience

@THCapper
Nov 2020: It’ll be in May 2021

@THCapper
April 2021: It’ll be at least June
https://developers.google.com/search/blog/2021/04/more-details-page-experience

@THCapper
I too miss deadlines

@THCapper
May 2021:
More clarifications

@THCapper
Original details
If a page hits the recommended targets for all three
metrics, it passes the web vitals assessment…
https://support.google.com/webmasters/thread/104436075/core-web-vitals-page-experience-
faqs-updated-march-2021
“
”

@THCapper
Original details
If a page hits the recommended targets for all three
metrics, it passes the web vitals assessment…
The page experience ranking impact will be the same for
all pages that are in the good range for all Core Web
Vitals, irrespective of their individual Core Web Vitals
scores.
https://support.google.com/webmasters/thread/104436075/core-web-vitals-page-experience-
faqs-updated-march-2021
“
”

@THCapper
May 2021: More clarifications

@THCapper
It is not the case that unless you reach the good threshold
for all of the Core Web Vitals metrics, that you have to
reach the threshold to get a ranking boost…
https://www.youtube.com/watch?v=HWm6WNkHs90&t=2180s
“
”

@THCapper
It is not the case that unless you reach the good threshold
for all of the Core Web Vitals metrics, that you have to
reach the threshold to get a ranking boost…
In fact, it's kind of the opposite. You will get a ranking boost
for reaching the good threshold for all pages but beyond
that point, you don't get additional boost for reaching it
even better.
https://www.youtube.com/watch?v=HWm6WNkHs90&t=2180s
“
”

@THCapper
The 7 Wonders of the Web Vitals

@THCapper
What if I was already
getting a boost for
these

@THCapper
But I didn’t
fix this yet
What if I was already
getting a boost for
these

63,472 ,
30%
149,165 ,
70%
CrUX data
No CrUX data

52.81%
47.96%
88.11%
63.76%
29.53%
CLS LCP FID 2 of 3 All 3
% meeting threshold

@THCapper
More contradictions
https://twitter.com/willcritchlow/status/13971241334
78088704
More
contradictions

@THCapper
Does it even matter?

@THCapper
2.31
2.81
0.38
0.26
-
1.00
2.00
3.00
CrUX assessment
pass
CrUX data available CrUX assessment
pass (control for
availability or CrUX
data)
Top 50% quickest
pages
Average difference in rank

@THCapper
https://developers.google.com/search/mobile-sites/mobile-seo/separate-urls

@THCapper
There’s more to life than SEO(!?)
https://www.portent.com/blog/analytics/rese
arch-site-speed-hurting-everyones-
revenue.htm

@THCapper
Discover
• Massive traffic
opportunity that SEOs
are sleeping on

@THCapper
Discover
• Massive traffic
opportunity that SEOs
are sleeping on
• Far more responsive to
speed than organic

@THCapper
Well, what have we learned?

@THCapper
1. Prioritize high
traffic pages
… we can employ
techniques like grouping
pages that are similar and
compute scores based on
that aggregation …
-
https://support.google.com/webmasters/thre
ad/104436075?hl=en

@THCapper
1. Prioritize high
traffic pages
2. Metrics can be
gamed

@THCapper
1. Prioritize high
traffic pages
2. Metrics can be
gamed
3. But not at the
expense of
speed

@THCapper
1.Prioritise high traffic pages

@THCapper
Field:
 Representative
Lab:
 Artificial

@THCapper
Field:
 Representative
 As used by Google
Lab:
 Artificial
 Not Google data

@THCapper
Field:
 Representative
 Apples to oranges
Lab:
 Artificial
 Not Google data
 Scientific

@THCapper
Field:
• Representative
• As used by Google
• Apples to oranges
• Only viable for
existing, high traffic
pages
Lab:
 Artificial
 Not Google data
 Scientific
 Viable for staging
sites, new pages,
etc.

@THCapper
Field:
 Representative
 Apples to oranges
 Only viable for
existing, high traffic
pages
Lab:
 Artificial
 Not Google data
 Scientific
 Viable for staging
sites, new pages,
etc.

@THCapper
2. Metrics can be gamed
optimized

@THCapper
2. Metrics can be gamed
optimized
Some less obvious methods:

@THCapper
● Use facades for late-
loading content

@THCapper
loading content
● Move unstable
elements below the
fold

@THCapper
loading content
● Move unstable elements
below the fold
● Delay render until
elements are ready (!)

@THCapper
● Identify which
element is
“largest”

@THCapper
● Identify which
element is
“largest”
● Reconsider hero
images

@THCapper
● Identify which
element is
“largest”
● Reconsider hero
images
● Drop big assets
below fold

@THCapper
The secret to FID:
Human manipulation.

@THCapper
First Input Delay
Do I need to click
immediately?

@THCapper
3. But not at the expense of
speed

@THCapper
https://developers.google.com/search/blog/2020/11/timing-for-
page-experience

Tom Capper Mozcon 2021 - Core Web Vitals - The Fast & The Spurious

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