Was this dumb luck on Twitter’s side? Perhaps. Luck always plays a larger role than founders, investors, and the media would like to admit. But a major difference was that Twitter could draw on numerous networks for advice and help that Tumblr could not. For example, Twitter was able to bring in Dick Costolo, a savvy executive with prior scaling experience at Google. In contrast, even though Tumblr was arguably the most prominent start-up in its New York City ecosystem, it couldn’t easily draw upon a pool of local talent who had experience dealing with rapid growth. According to Greylock’s John Lilly, for every executive role that Tumblr needed to fill, there were less than a handful of candidates in all of New York City. This paucity of talent made hiring difficult; the company was reluctant to replace existing employees due to a lack of better alternatives. Without the ability to hire an executive team that could blitzscale, Tumblr decided to sell the company.