There were some reports a few months ago about new pages ranking based on social signals alone, but I don't remember the searches being highly competitive. Once you highly competitive territory, my impression is that you need a wide variety of signals working for you.

One can only do best they can with the tools and knowledge available. There is a larger paradigm which is not "the web" that needs consideration: "ebb and flow". I wonder if the major SEs have integrated that into their algos... I think not, but I don't have an in to their inner circles. But there is no doubt that there is "ebb and flow" in all things social, as Toynbee's Pendulum has proved too many times, and there will be a swing. Web wise, that's generally 6 months to a year for any real change.

There are many many factors that you're not considering, like, backlinking domains, authority of those links and of that domain, age of the domain, and so on. As far as I know there is no proof of social likes and + affecting SERPs "actually".

ACTUALLY. Google is trying to include everyday more human and social factors inside their algorithm, so it's good to make social media optimization, one day this could affect your rankings.

Another thing to remember is that Google has changed the way they rate URLs in Google +, summing every + to the domain so, even if you're down your competitors, but your result shows 50 more likes (maybe with one friend of that guy listed) people may consider click on your site before.

In conclusion, you're doing better than your competitors in social media? That's good, you'll have to raise your authority, gain some really good links and maybe you could surpass your competitor.

For what it's worth...

For our ecommerce site, the folks who come to our site through facebook have a higher conversion rate than those who come through the search engines.

So while it might not help with rankings, it definitely helps with sales (in our case, anyway).

And this is "organic" facebook traffic, since we don't use facebook ads.