I've heard that when you make SEO driven changes to your site you can experience a traffic dip before things start to improve. Is this true and if so then can anyone point to a good resource that examines this effect and presents the findings?
It need NOT cause traffic drop unless the person seriously messes with a) page titles of already ranking pages b) changes indexed url's without 301 redirecting them thereby losing link pop c) messes with internal linking structure.
The above things can potentially disturb a page already ranking well and subsequent loss of organic traffic.
As the seo campaign moves forward the link building can help regain lost rankings and hence traffic.