Dropping in pages indexed, but increasing in ranking

[cangoou]

Hello! On a good visited community-site with many new threads/pages a day, the number of indexed sites dropped from over 4000 to about 400 in mid of march. The ranking of single keywords and the traffic is still increasing slightly, but I was wondering what could cause such a drop in indexed pages.

[tedster]

The most common reason is bugs in the site: operator reporting. Has the number of pages actually getting Google search traffic changed?

[cangoou]

Thanks for your reply. No, the traffic from Google organic is still the same, seems to be increased a bt in fact.

The Q is: Will only the display of the site:-operator be buggy, or will Google really find less pages (which should result in less traffic from Google as the longtail should be trimmed).