What exactly can the google site: command tell us

Google site command

[doois]

I have a 526 page site with PR5 that enjoyed the top position on google. Recently and without major changes to the site, google knocked us down to page 7. Running a site command, the homepage comes in at 170 of the 526 pages.

The site did suffer a canonical problem (thank you Dayo for clarifying with 301 correction) but the site has since been spidered and the problem seems to have been corrected. The results of the site command and the serp rankings dont reflect this 'fix'.

Waiting game or does the site command show something more deep rooted? How do i get my homepage back to top rank for the site: command?