"This index is built on a weighted points system which considers the following factors: website traffic, social media following, social media engagement, employee count, page rank, inbound links, and SEOmoz domain trust score. Funding information is provided to give the reader context, but is not factored into a company’s ranking position."
First of all, many of these factors would seem to be correlated and self-reinforcing (is the ranking data published somewhere?) Also, the vast majority of these factors ultimately come back to publicity -- which is not necessarily remotely correlated with success outcomes. Companies like Invite Media, which certainly qualify as a substantial success, would rank low on this index.
Ultimately, this index seems to reflect less about which startups are actually sound businesses per se and more about which ones are generating excitement and hype. Ultimately I'd be more excited to see an index doing the former not the latter. Are the data sources for this linked to and/or explained anywhere in greater depth?