It's been slowly going downwards over the year - the page itself is more than 2 years old, only with minor modifications during this time, basic texts have remained the same.
No changes correlate to major algorithm shifts as far as i can see.
Could google penalize that hard for the content age? This is a business frontpage - so there really is not that much to update on that particular page.
Our link portfolio hasn't seen major changes in years - infact, it seems to be pretty much the same. I went through the first 300 or so as reported from GWT on random check, didn't see anything seriously spammy, many of which are high quality organic links. HOWEVER, moz tools says we have ~8600 inbound links, and GWT says total links 854,161
Something seriously wierd is going on for the keyword since #2 position is held by a site with 1 external link inbound as per moz tools, only thing they have pretty much is 99 google +1s.
Downloaded more sample links and still cannot see anything seriously spammy. There are some scrapes and people copy pasting offers or announcements, but not much. There's also some semi-spammy sites which list best offers etc.
GWT tells no manual actions.