Content Writers can't ignore this social traffic generator and those who have seen spikes in their site analytic reports truly know its power. It's the best social traffic generator today and hence should be generating lot of curiosity in content writers mind - "What's the algorithm ?".
Though its quite logical that such company can't keep their algorithm transparent and might keep changing it after intervals but still its good to keep guessing so that one can make their strategy more friendly to StumbleUpon.
1. Followers
More the number of followers , More is the probability of your Stumbles being accessed and liked and hence faster propagation.
2. Likes
If your site keeps getting likes , your pages keeps getting hits.
3. Reviews
Though its not a major factor , still i feel it plays a role.
4. Traffic limit by StumbleUpon admin.
I believe that stumble upon admin have full control over the traffic being directed to your pages. I have seen consistent referral traffic for some of my pages over the weeks which affirms my belief.
5. Website Rank
Site rank does play a big role as i saw increase in quantum of traffic with change in my Alexa rank.
6. Paid Discovery
If you can't earn it, Buy it :)
So Let's start by building followers. Follow us and we will follow you.
http://www.stumbleupon.com/stumbler/buggybread/likes
http://www.stumbleupon.com/stumbler/buggybread/likes