Think stock market, keywords are assigned into groupings much like stock are assigned a sector. Every grouping has related keywords much like stock sectors have different flavors of companies within them. If your site is about "technology" then it is expected to cover the sector well so if Google finds your site lacking in coverage it probably doesn't do as well. Similarly if you cover the same thing redundantly to excess you may fracture the strength of any given keyword sets your pages maintain.
Without seeing a list of specific words you can't possibly get it 100% right, nor should you since that would also look questionable, so the solution? Just write for people and don't focus on keywords save for the page title and to make sure you have at least *some* keywords related to the subject.
Other possibility - Google is tracking webmasters and the people working on the site are currently highly trusted? It's not hard to figure out who the site owner is, they have your IP etc from the first moment you ever log into any Google product (gmail, adsense, adwords etc) and they see which sites you frequent via the +1 button, analytics, adsense etc. It wouldn't take very long to get an idea about what type of person you are, been on a blackhat forum a little too often? Hmmmm
Heck, have you been in webmaster related forums too often? That might work against you too. Maybe the site owners aren't into SEO? lol. Toss these into the other factors bin though don't weigh them too highly.
It could be as simple as: Pages gain history as they age, both good and bad, and the new site simply has no negative signals, yet.