Vale Tudo, or no rules fighting, was very popular in Brazilian throughout the 20th century.  Many excellent martial artist went to Brazil to fight in Vale Tudo to test their skills against Brazilian fighters.  Real fighting, competition, and sparring is the only way to refine a martial art in to something effective.  The Gracies honed their skills and their art against many fighters from around the world.  In this fight a Karate fighter takes on a Gracie.  It is very apparent that unlike modern MMA karate fighters such as George St. Pierre and Lyota Machida, this man did not also cross train in a grappling martial art such as Brazilian Jiu-Jitsu or submission wrestling.  Many martial arts are very ineffective when dealing with a grappler and can be greatly improved by also training ground fighting.  Bruce Lee once said he could take a college wrestler and train them in boxing for a year and that person could beat any martial arts master of the day.  The UFC and other mixed martial arts organizations have proven Bruce Lee to be correct.  If you only train one martial art, it should be BJJ, if you train more than one then one should be BJJ.  This video illustrates this.