One: the page had an inordinate amount of detail, including Silver's high school awards and favorite foods. His page read more like the resume of a recent college graduate - which he was - than a typical Wikipedia article.
Two: the information was incredibly detailed and included a comprehensive set of personal data, the sort of over-the-top detail you would expect from a statistician. And very promotional in tone - go find it and look for the "view history" link, see for yourself, it's still there.
Three: at the time, the only other pages edited by "Mack2" were pages about baseball statistics, Soviet history (Silver is reportedly Russian), and Silver's company and co-workers. Nothing else. Does that sounds like a disinterested journalist documenting an interesting topic? Hardly. I suspect it was Nate Silver himself, writing his own PR, using a fake name - just like he eventually acknowledged doing at DailyKos.com.
I had the sense that Silver was promoting himself there, and I thought he did a fantastic job at it. I'm guessing that once the NY Times picked him up, he may have hired a professional PR agent at that time, or the NY Times got him one - it's a win-win for them, after all. PR agents and journalists go hand-in-hand, any there are individuals who do both, or change jobs from PR to journalism and back - all the time. Not unusual at all. PR is a big aspect of newspaper work and journalism.