SocialsThis time last year, social shopping was The Next Big Thing. Driven by the insane adoption of Pinterest, everyone from old school retailers to new ecommerce sites buzzed with excitement over social commerce. By April of this year, the industry had raised something like $302 million.

One year later, the idea of social shopping has matured beyond its humble beginnings. F-commerce, or storefronts on Facebook pages and apps, is basically dead. Facebook has breathed new life into the idea by taking commerce in-house in the form of gifting and focusing its social commerce efforts on the marketing side. Meanwhile, the second-largest social network, Twitter, wants nothing to do with commerce, positioning itself firmly in the “ad-supported media company” category. Brands don’t seem to care too terribly much about Instagram yet, and they certainly have no place on LinkedIn. That leaves one other major social network, Pinterest.

This time last year, Pinterest’s rapid adoption had investors and brands drooling over the possibilities. Pinterest is just so consumption friendly — the image-driven pinboard format has what I like to call “stuff-lust” baked into its core. It even refers to itself (or at least did at some point) as a “social catalog” on AngelList. It’s a “virtual pinboard” on its website.)

The natural assumption was that, because Pinterest was all about consumption, Pinterest browsers would convert into buyers more often than users arriving from Twitter or Facebook.

It was a big assumption.

Depending on whom you ask, Pinterest conversions have been falling since January. They remain around a third of Facebook’s. And order sizes are, on average lower. (Some studies argue Pinterest traffic are bigger spenders.)

No matter the study you want to believe on basket sizes, conversion rates or traffic, one thing has not made retailers happy: Pinterest has taken its time opening up an API for them to build on. Brands, retailers, investors, and SaaS startups have been anticipating it since February. Since nothing has materialized, companies from Buddy Media to small, Pinterest-specific startups have been offering lightweight scheduling and management tools in the interim.

So brands are investing their social dollars into Facebook, and have seen reciprocal engagement on the platform. Of the consumers surveyed by social commerce platform 8thBridge, 63 percent say they share products on Facebook, but only 22 percent share on Pinterest. On Facebook, 99 percent of the 500 brands surveyed had a presence with an average of a million fans; 78 percent of brands were on Pinterest. Facebook drove 2.9 percent of a site’s traffic on average, while Pinterest only drove 0.13 percent. Which is to say that traffic from Pinterest was on average less than one twentieth that of Facebook.

The gulf is even bigger in case studies from sites like Fab.com, where Facebook drives 24 percent upstream traffic. That leads to a 15 percent conversion rate for socially discovered products. Meanwhile Pinterest accounts for just 0.55 percent of Fab’s traffic. Deb Shops, Sears, Nasty Gal, Petflow.com and Coastal Contacts all saw significantly higher boosts in traffic from Facebook than they had from Pinterest. (Twitter was typically comparable to Pinterest levels.)

Pinterest may still hold the great hope for social commerce, but Facebook still rules for now.