People do a really crappy job of comparing the success and growth of competing early-stage companies. It’s generally WAY too early to call when companies are just a few years into the (endless) race. Take Richard McManus’ post “Tumblr Leaves Posterous in the Dust“. It’s an interesting post and fine piece of linkbait (I’ve been hooked!), but it’s a pretty simplistic argument.
Let’s ignore Compete entirely (Quantcast is based on real numbers and tends to be more trustworthy, IMO). Here’s the graph that Richard tossed up.

Is Tumblr winning the race? Absolutely. But they started running before Posterous even made it to the starting gates. So the big question is: What did Tumblr look like around 13 months ago? It looks like they were at around 7m global uniques (compared to Posterous’ 2.5m most recently). Certainly ahead, but hardly leaving them in the dust yet.
The big question is this– How powerful is the first-mover advantage? I’m not convinced that it’s that powerful in this particular market. Eventually Tumblr will plateau. The question (that can’t be answered now) is this: Will Posterous plateau at the same point in time or the same point in their product’s lifespan? If it’s the former, Posterous will indeed be eating dust. We’ve got a long distance race where one runner started off slow and is accelerating right now. We’ve got another runner who started the race WAY late but is showing solid acceleration. Either way, 2 years into either companies lifespan is a pretty silly time to call a winner. For a stark example, compare Twitter at year 2 to Twitter at year 6.
Incidentally, this is exactly why it’s silly for people to dismiss Twitter’s threat to Facebook (even though Facebook currently dwarfs Twitter’s traffic and signup rate). It’s not just about growth rate. It’s about acceleration and how much fuel you have in your tank. In other words, it’s about how close you are to the inevitable point where your growth plateaus. For Tumblr and Posterous (two awesome companies that I think have a bright future), it’s WAY too early to call.





