Black Lagoon wasn't written by Urobuchi. He wrote a light novel based on the manga, and the anime was also based on the manga.
Also, double posting is against the rules so I'm gonna preemptively give my thoughts on Valvrave 6 based on what I think is gonna happen even though I haven't seen it yet, just in case no one posts between now and then: "Holy fucking hell yes, anime of the year 2013. My boner is now infinitely huge."