Nothing happened. This data is incomplete, "expectation that the dip won't look quite so severe when additional information comes in." And if you look at the other charts, everything is just fine. All this means is that more small deals were done in Q1, rather than big deals. Just stick to comparing A, B, C rounds, not overall value of pre-money rounds.
Just for the record, I remember ZeroCater's demo day and it seemed like they were already off and running without needing to raise more money. At least that was the feeling I got when listening in the crowd.
Anyone can pop up their alexa ranks in the short term, but long term you still need retention, which equals traction. Typically higher the rank, the better you're doing.
I basically agree with this, putting an order on this list might have irked some people, but a list of companies to follow in no particular order might have worked better.
I like most of your lists and creativity, but this one isn't very helpful and it feels like you're reaching. After a site cracks the Alexa top 10,000, it becomes a lot harder to move up and should be worth a lot more on rankings.
You should look at Alexa for world traffic vs US traffic, not many YC companies are targeting international users yet but are very successful in the US. Take into account FB/Twitter followers as well. Even though followers don't determine success, companies that don't grow their social side of the business usually indicate a slow growth or nongrowth business. Also goes to show how much extra time or money they have to throw at it.