One of my earliest SEO wins involves a tale of two sites.
Site #1 dominated the rankings. It ranked #1 for "linux hosting", along with hundreds of other hyper-competitive, internationally sought-after results. This went on for years.
Site #2. That was a mystery. About as old. Also commercial. More authority from inbound links than the other. No spammy practices. I was running both from the start and ran both the same way. Yet the second site just wouldn't rank for anything.
So I struggled. I posted on the Search Engine Watch forums. Back then, Danny Sullivan was in charge, and that was basically the only place you could find those mythical SEO gurus.
There, I gathered lots of terrible-to-passable advice. But for the most part, it stumped everybody.
Then I did a crawl. I realized that all the internal links were redirects. It was nearly invisible to the naked eye because it only involved a trailing slash at the end of every web address. Menus, direct links to other pages, and so forth: all of them lacked a slash at the end of the URL, and all of them redirected.
So I fixed it.
Then, after 2+ years of struggle, I watched site #2 blow site #1 out of the water. Practically overnight, it was ranking #1 on every expensive telecom-related search query that I was after. From "dedicated servers" to "[CITYNAME] colocation" and beyond.
From that point on, fixing redirects seemed to be one of the most reliable SEO magic tricks in my playbook.
Why Did That Work?
Almost nothing in SEO happens in a vacuum, so we're never certain. Then, my uneducated guess was just that I was signaling that I was a more attentive website-keeper.
As I've leveled up my SEO skills, I learned that Google had told all of us, as direct as can be, that PageRank "decays".
This occurs through what Google's own patent filings describe as "the dampening factor".
In 2005, the SEO trick of the day were these "link wheels". People would link to "circles" of different websites and try to throw Googlebot into an infinite loop for infinite link value.
When you think about it like that, decaying PageRank just makes sense. Even before considering that Google's going out of their way to shut down those shenanigans directly. You shouldn't be able to pass an infinite value to your own stuff by interlinking in a circle.
Might Google dampen the value of redirects so that each redirect has incrementally less PageRank value?
That's been directly stated by Matt Cutts more than once.
It's even in Larry Page's original PageRank patents.
The message we were given? Redirects lose some PageRank value through each iteration. This occurs in exactly the same manner as links.
Then, it all changed (maybe).
Last week, Google's Gary Illyes tweeted:
30x redirects don't lose PageRank anymore.
— Gary 鯨理／경리 Illyes (@methode) July 26, 2016
Thanks, Gary -- what am I supposed to think now?
Look, I have no reason to doubt Gary. Or Matt. Or Larry. Google's staff have said plenty of things over the years that never panned out in testing. Self-contradicting advice from Google has been more the norm than the exception.
Is it because their agenda is to get everybody acting a certain way? Do ends justify means?
Maybe. But probably not.
Just like a lot of other contentious SEO topics, Google and actual testing can disagree and both be right.
Ranking factors are independent functions and Gary is only talking about one of them. Here's an example.
Redirects, especially chains of them, slow everything down. And we know this:
I'm sure some of you can find plenty more conflicting scenarios if you thumb through the ranking factors.
I'll take Gary at his word until I see conflicting evidence, but for now, we're downgrading Redirected Internal Links from Probable to Iffy on the list of direct, negative factors.
Still, if you want competitive SEO, take nothing for granted. The best practice is still to avoid unnecessary redirects. All that's up for debate is how much impact this has on your rankings. You still know that performance is a ranking factor. I'm still looking back on decades of data that dramatically contradicts Gary's tweet.
Whether linking to redirects (and redirect chains) directly harm your SEO in 2020, well, I'll leave that to you. I'm going to go on polishing this and any other evidenced factor that I can directly control.