Copeland - 5:29 pm on Jul 28, 2010 (gmt 0)
I'm a firm believer that link age is an integral part of the Google algo. In fact, I think age carries too much weight in the current algo. I have only indirect evidence and speculation as proof with as conducting a test in the long term requires holding too many variables constant (including making Google not change the algo while we test). My take:
An inordinate amount of old sites -by "old" I mean sites that were launched pre-Google dominance when links were given more freely- have strong rankings in competitive verticals despite below par content and no evidence of proactive link development. Why do they rank competitively then? Because they obtained good links 10 years ago when links didn't matter for search rankings. These links have gained value over time and make these sites seemingly impossible to dislodge in the serps. I have obtained some first hand knowledge having participated in acquisition discussions with "old site" owners. During due diligence it became wildly apparent that the site owners had little clue about link development. Their content wasn't unique or even particularly good so they weren't attracting new links (except maybe by ranking high in the serps, the best link bait you can have). Since they weren't proactively securing new links, why did they rank? The only conclusion I can ascertain is that Google values a link incrementally more with each passing day.
This begs the question though, why would Google value a link incrementally more with each passing day?
1. The longer a link stays in place the more of a sign it is to Google that the link must be legitimate. The counter argument is, of course, that the link could just be stale. However a stale link is likely to rest on a stale page. A stale page should lose inbound links over time, reducing it's PR passing power. So age and staleness are likely independent variables, or at least not co-dependent. An aged link on a page that isn't losing PR is thus a sign to Google of quality.
2. Google using age as a positive variable is, IMO, the single biggest weapon they have in fighting paid links. Here's why: Once a site starts buying links for search purposes they can never stop. If you stop paying for a link, the link goes away and all your money is down the drain. In my view, the purchasing of links for SEO purposes is the biggest gripe Google has with the SEO world. Reason being is it is the most difficult for Google to detect and police. Given this, if Google wants to fend off the attack of paid links on their algo, the best way to do so is to hit the offenders where it hurts the most: their wallet. By making age a valued variable in the algo it forces buyers of paid links to throw cash at links for a longer period of time to derive full value of the paid link.
At this point I am pretty convinced the algo favors age and that it favors it too much, to the extent that I actually feel Google is broken. The best content is not being served up. Instead we see old sites and the sites with the deepest pockets.