They are not "core" devs. It's an error in Softpedia's article. See
https://bitcointalk.org/index.php?topic=1290358.msg13378009#..."""Softpedia published an article by the title of "Amid Bitcoin Centralization Worries, Core Developers Start New Currency Called Decred". It looks like confusion started here about the word "core". The original title put on the press release was "Bitcoin Developers To Start New Digital Currency". Media houses seem to rewrite these, so it was only a matter of time before this happened. This got picked up by Slashdot and now it's on their front page."""
The staff working on Decred is https://companyzero.com/our-team.html