Looks like you did lots of changes. Did you change domains? I don't know how you validated whether or not these changes improved matters or not. You said you moved to a dedicated server from what? A vps? For example a dedicated box isn't necessarily faster than a vps and subject to what you invest. Did page load times worsen or improved? Any connectivity problems? Did you change the dns settings?
You removed 2.5K of pages but you did not place 301 redirects to equivalent or nearest pages, since pages removed, were contributing to your site's rank and these requests are associated with your site's content.
Then you did various content and link changes, how did you validate those? Are you saying you paid somebody and he placed a ton of external links to your domain to improve SEO?