I was hired for this company to perform SEO, shortly after google had scheduled the release of a new search algorithm that would reduce views on pages that were not mobile complaint. ATTO got the effect of this with a 50% drop in traffic in a matter of days. A website with over a million views a month it needed to be overhauled. I was tasked with a complete redesign on the website and its 800+ pages. I monitored and improved SEO on the pages over time as well as slowly gained back that 50% loss in traffic. You can checkout the other contributors for refferences.