Twitter has seen three departures in recent weeks, with both TweetDeck founder Iain Dodsworth and Platform Director Ryan Sarver both announcing their exits today. The third is Jason Costa, who has been Developer Relations Manager at Twitter since early 2011, who actually took his leave quietly earlier this month.

We’ve confirmed Costa’s departure, as well as his destination, which is the collection, discovery and sharing site Pinterest. Both Sarver and Costa worked in the department of Twitter which was charged with communicating policy to developers and helping them to adapt to the changes that the platform has been undergoing in recent months.  Three departures for Twitter as Dev Relations Manager Jason Costa heads to Pinterest

This leaves two large holes at the top of Twitter’s org chart in the developer relations department, which has seen its role transmute significantly as the policies which govern it have been molded to the product’s new direction. That direction has placed Twitter in a position to control the look and feel of the ‘canonical’ Twitter experience more fully. Which has, in turn, allowed it to quickly iterate on a series of products that are more attractive to advertisers and brands that want to ship media-rich messages on the quickly growing messaging platform.

Twitter CEO Dick Costolo spoke at the D11 conference this week and touted the speed at which the company was innovating internally. “Within the framework of direction, we have almost 1,000 engineers at Twitter. I’m looking at those guys to create,” said Costolo.

Previously, a major contributor to innovation at Twitter was the network of third-party developers to which Twitter allowed nearly unfettered access to its API. From that community came things which are now part of the very core of Twitter, like Retweeting and even the bird iconography.

“I think we’ve been very clear that we want to be the place where people go for the home timeline experience,” Costolo said at the conference. “We also still allow the free licensing and API use of the home timeline so that people can create different kinds of timeline experiences. But we only allow them to get to a certain size until they have to create a formal relationship with us.”

This focus on companies which use its data for analytics, sussing out trends and resale opportunities has no doubt changed the tempo and temperature of conversations with developers and therefore the roles of both Sarver and Costa.

Costa isn’t the only ex-Twitter-er to end up at Pinterest, as Product Designer Connor Sears left the company in late 2012 to take on the same role there. We don’t know what he’ll be working on over at Pinterest, but we do know he’ll be joining officially in a couple of weeks.

Pinterest continues to attract design and developer talent and, after listening to CEO Ben Silbermann at D11, it’s not hard to see why. His talk was impressive, largely free of bombast and jargon and painted the picture of solid leadership to a growing company that was still finding its way. AKA: Exciting.

Image Credit: Jeff J Mitchell/Getty Images