my friend is running an adult forum (using vB), he has been complaining on for a while now that his google search links are going down by the day - probably after the release Google Panda (my expectation, I didn't reveal him that as I wasn't sure about that). At one time when his site was searched via, site:site.com it gave over 150k links now it gives barely 1.5 - 2k links constantly changing. What could possibly be the reason and what advice can I give my friend to help him regain good searches back to his forum ? JFYI, his PR hasn't dropped its been same all along.
Is it an active forum? Updated content/forum posts can help. Sounds like his forum got downgraded for some reason and it could be related to a Google update.
Its an active forum but it was down for a week or 2 few months back as he had some problems migrating server - his host shut down, he had to wait for the backups to arrive & so forth. He did mention his sitemap generator got screwed up after the migration, so he had to reinstall his sitemap plugin which removed lots of dead links as well, other than that I don't have much of first hand experience on his admin side.
Your sitelinks are decreasing, probably, for two reasons - Your backlinks are turning nofollow - The pages with which you were linking have removed their backlinks Since your forum was down for a week, many proactive webmasters remove links from such websites. I thinks, this is the prime reason for drop in links.