A means or manner of procedure, especially a regular and systematic way of accomplishing something. These two definitions really sum it up. Whether you realize it or not you use systems everyday in your own life. What you probably didn't realize is that you had to think of all the ways to get around it. You spent time mapping out in your head what streets to take and which to avoid to meet your goal.
Gambling systems are no different.
Just by the very nature of Roulette there are better selections to make than others. A good system will allow you to make better selections then just arbitrarily picking a spot on the table. A good system will also allow you to stay in the game longer and give you a better chance for making a profit. You bet they did, and so does every other team out there. Some systems are better than others.