I recently changed my permalink structure from %category%postname% to just %postname% as my categories and postnames where the same so I thought it looked spammy. I just did this on the spur of the moment and didn't really think of the consequences as I assumed this could only have positive affects. Well looking at my site stats for this month they took a HUGE dive on the day after I made the changes. I am consistently 70% down on what I was before I changed this. The only other difference in my site is that I added 5 new articles the drop in traffic has to be because of the permalink changes. The thing is that if you go to the old URL it redirects to the new ones. So I am not sure why the traffic has dropped so much. I am writing this as a warning I guess but also to ask what I should do? Should I change back to the old permalink structure of just leave it be and wait for the rankings to pick back up? Incedently if anyone is looking to change their permalinks then there are plugins which claim to be able to do it without affecting seo/traffic.