I have drawn a conclusion.
The level of effectiveness in your grappling training is directly related to how injury prone your training methods are.
The origin of Judo is Jiu Jitsu. Kano Jigoro took the evil moves out of Jiu Jitsu to make Judo. He also developed an emphasis on Randori. Soon he was challenging Jiu Jitsu schools and winning (see http://www.jiu-jitsu.net/history.shtml). To be able to practice and refine technique with an opponent applying realistic pressure develops the effectiveness of the technique. If you or your training partner does not sustain injuries in the process of training, more training can be done.
Count Koma brought Judo to Brazil. According to the link posted previously, Judo had underwent a change in philosophy around the same time Koma made his way to Brazil. More focus began to be put on ne waza (ground fighting). Helio had a small frame and adjusted his ground game to get leverage over his stronger oppenents to win matches. Thus, BJJ was born.
Also, sport Judo keeps it's primary focus on throws. Ne waza techniques have a very short time limit so the focus on the ground relies on strength, speed and athleticism. In my very limited experience, most of my injuries have been derived from these attributes used by my training partners.
Sambo is also derived from Judo. There are many evil moves that cause much pain to legs in the training of Sambo. Rickson and the Machados would enter Sambo tournaments and win. Do many Judo or Sambo practicioners win @ NAGA or other grappling tournaments?
But really, the proof, in my opinion, comes from the ADCC.
Almost everyone that places has a background in BJJ (Mark Kerr is a notable exception).
I guess this kinda harks back on one of my previous posts.