Down In Google SERPs

What do you think of this case

[Noximus]

Hi All,
I have a site, quite old about 4 years. All the time the site was on the first page of SERPs for the very competetive travel related keyword. The place of the site in serps varied from #3 to #9. Two months ago the the site began to go down in serps. It got the place #11 than place #16, 20, 23, 28 and now it is on the sixth page. When The site began going down I began to take usual measures what we all do in this case, swap links, optimize better, add content and so on. But nothing helped. There is one important thing also When I check my site in serps with "&filter=0" it is on the old places. Do you have any idea what kind of filter my site has got in? The site is quite big, several thousand pages. Please tell me if you have any ideas or have had the same exparience. In advance thank you for any comments.

Noximus

[brough]

I am having a very similar experience which I think is a penalty for duplicate content. Mid October my rankings for a great many terms began slipping from page 1 to page 2, and are now off the map entirely. The site, which is 7 years old and has tens of thousands of pages, is dead in the water.

Not completely dead: it's only one major section which has been affected. All of the other sections and subjects are just fine.

I had a similar problem earlier in the year... but I'm a very slow learner, and made the same mistake twice.

I hope this helps.

[oodlum]

When I check my site in serps with "&filter=0" it is on the old places. Do you have any idea what kind of filter my site has got in?

That's the similar content filter. As in:

In order to show you the most relevant results, we have omitted some entries very similar to the 2 already displayed. If you like, you can repeat the search with the omitted results included.

Clicking the link to see the omitted results adds the "&filter=0"

[SlyOldDog]

I've seen one knowlegeable person on this forum talking of a "slow death" penalty.

I have no idea what it is, but you might want to do some searches on that.