I'm afraid this sounds really generic and a bit desperate. I don't see any of the guiding principles really looking at Tumblr's strengths.
Also, the pattern of "diagnosis, guiding policy, coherent action" is copy-pasted from the book "Good Strategy, Bad Strategy"[1]. I've seen this internally at companies and even though the article is a great read, the application leaves much to be desired.
[1] https://www.mckinsey.com/capabilities/strategy-and-corporate...