Why could the site go down?

Question

Search Engine Optimization

We have a website. He had certain positions in Yandex. I started to optimize it (besides the catalog of services, I decided to put the keys in the title of the sections "About the company", "Clients", "Reviews"). I made it like this: "Cargo transportation - about the company", "International cargo transportation reviews", "Clients of the transport company" ... After prescribing the keys, the site sank in positions in Yandex ... Could this negatively affect?
PS Before that, the title was the same as the title of the section...

Answer 1

Well, what can be understood and suggested here? The reasons for subsidence can be dofiga and more.
The fact that you have optimized the pages About the company, Clients and Testimonials will only affect the traffic of these 3 pages.
What positions were there and for what requests? What exactly was changed? What positions sank for what specific requests? What pages are sagging?

Answer 2

filter for re-optimization - the most frequent, insidious and difficult to remove