OK,
> So-- what's your site
I "look after", in a very loose sense, lots of sites.
> what kind of techniques were you using for SEO
Lots, with varying degrees of buy in.
> what phrases had you optimized for
Too many too know
> what were your old results
Lots of really good, relevant traffic
> where are you for those phrases now?
About the same spot

With one notable exception: A site that dropped like a brick. Said site was aweful, and got by on tricks rather than "enhancements", i.e. it used good practises, but these were added to bad pages, not to content that was already excellent. It is also a site that is small in its industry sector, without any really good industry big wig links. Interestingly, it ranks well for the tweo word search "{SPECIFIC PRODUCT TYPE}" but not the three word search "{PRODUCT TYPE} {PRODUCT}", so maybe there is some sort of filter involved for specific searches, or maybe there is a keyword density filter on (as every page has a LOT of the word {PRODUCT} on the page).
Either way, this site never deserved good rankings, and now it is gone, the SERPs on which it did well are significantly better.