I supported more than 40 projects on Kickstarter. Almost all were successfully funded and almost all of those have delivered or are clearly on their way to deliver.
But my success rate has nothing to do with self fulfilling things. It's just that I do not just support projects because I like the idea, but because I check the details and ask myself if the project seems reasonable and the project leads know what they are doing.
Now if I can do that, somebody with a lot more insight in this process, like somebody working for Kickstarter, can do that even better.
And thus most of the staff picks succeed because the Kickstarter staff tends to pick projects with a good chance of success.