The comment_reply_link has a nofollow attribute that can not be removed at theme level, this is a major problem for SEO reasons:
Google has changed how it treats nofollow links, originally it would treat them as if they didn't exist, the anchor text would be treated as body text, no PR (link benefit) would be passed or lost due to using nofollow.
Currently Google black holes (deletes) the PR (link benefit) that the link would have passed, so rather than treating a nofollow link as not existing it now treats it like a link but instead of passing PR (link benefit) it destroys the link benefit that could have gone to other pages that was linked to from a page.
This is a big deal for the comment_reply_link function since on blogs with a lot of comments each comment has a nofollow link!
If you set your blog to have 50 comments per page that's at least 50 nofollow links on heavily commented posts and that's a lot of wasted PR/link benefit when it comes to Google rankings.
Picture a page with 100 link total (including the comment reply links) with 50 being comment_reply_link, that's at least 50% of that pages link benefit lost.
For this reason it is highly advisable to remove the nofollow attribute from this function or at least supply a way to create this link without a nofollow attribute. Not even sure why it was added in the first place, nofollow is not needed on a link like this, Google etc... will determine the links are to the same content and combine the URLs.
Seo-dave 00:27, 22 July 2009 (UTC)
Surely the comment links are only of benefit to folk who wish to spam their own sites, rather than to the site that has the links on them? Anyway, this discussion may be better placed on the wp-hackers mailing list, where such things are pondered over. I'd suggest posting your thoughts on there. mrmist 05:55, 22 July 2009 (UTC)
I think you misunderstood my point, it's not comment links per se, (which are also a problem, but not easily solved like this one is) it's the internal reply to comment links as created by the comment_reply_link function. The relatively new reply to comment links are internal links so the only person that can benefit (in theory) is the site owner (as an SEO consultant I plan to optimise them, but that's a post for one of my sites :)). The problem is with a recent Google change, all nofollow links now destroy link benefit, before they would preserve link benefit, so having 50 nofollow links on a page is equivalent to linking out to 50 sites you don't want to in PR/link benefit terms and this is VERY bad SEO wise. You could very easily half the internal PR/link benefit of a site when it comes to Google, this means internal deep content pages are going to have their SERPs damaged just because of this function and an unnecessary nofollow attribute!
It's a simple fix, in
Remove the nofollow attributes associated with the comment_reply_link function.
Personally this isn't a problem for me since I can edit that file when there's an update, but for others who don't want or know how to edit core WordPress files they are damaging their sites search engine optimization in Google by using the new comment reply links in themes! I've not enabled them over all my themes because of this.
I'll take a look at the wp-hackers mailing list (wasn't aware there was one).
Seo-dave 11:10, 22 July 2009 (UTC)
I've since researched this and can see what you mean (almost!) so yes it seems reasonable that you should either be able to override this behaviour or that the nofollow is removed. I'd suggest either the hackers list or maybe a trac ticket would be the way forward. So long as you can explain the concept to others - I suspect this is not well understood outside the SEO communnity.
mrmist 11:34, 22 July 2009 (UTC)
I think that nofollow on the reply link might prevent search engines from unnecessarily following the link, which would just reload the page with the comment form set up for the comment-to-comment reply. (Blocking '?replytocom' in robots.txt should fix that, though?) I'll leave the question of whether this should be removed as a default or not to others.
There *is* a 'comment_reply_link' filter you can use to strip out the nofollow via a plugin or theme function. Why not use that for now?
dougal 11:20, 22 July 2009 (EDT)
I tried the hackers list, posted the info, no response! Not sure how to submit a trac ticket, so will have to look into that. Been researching filtering the nofollow from the link, but haven't figured it out yet. How would you filter the nofollow at theme level?
Seo-dave 16:32, 5 August 2009 (UTC)
Submitted a trac ticket at http://core.trac.wordpress.org/ticket/10550. filosofo comment about turning the link into a form sounds spot on. Hope it gets incorporated into 2.8.4 so I can update my themes with this function :)
Seo-dave 14:34, 7 August 2009 (UTC)