Echonest is confusing the band "timeflies" with the rock band "time flies" as seen in the request below. The requested artist id points to timeflies, but many of the results are either from the rock genre, or from the band "time flies".
http://developer.echonest.com/api/v4/playlist/static?api_key=API_KEY_HERE&artist_id=spotify:artist:6dC0rIJNLSFZwqckLgXJ8p&format=json&results=100&bucket=id:spotify-WW&bucket=tracks&limit=true&type=artist-radio