Thought for the Day
I know it sounds crazy, but I can only speak from a variety of experiences in the past couple of years: sometimes conducting SEO without a site redesign does not produce results compared to when a site is redesigned.
I only have anecdotal, not empirical evidence at this point. On the one hand, it seems odd to me that a more professional, polished site would rank better; search engines, to my knowledge, do not include aesthetic factors in their search algorithms.
On the other hand, I have optimized sites for clients who chose not to hire a professional to upgrade their site, and those sites have not performed as well as those that did make such an investment.
Thought I cannot count out other, unrelated factors such as the particular industry, market, etc. that may be preventing larger ranking and traffic improvement, I have a hunch that design and SEO performance are interrelated.
My theory at this point is that a solid, professional redesign is more likely to include search-friendly design factors, content display, and less likely to include technical barriers, though this is by no means an absolute.