I wasnt even basing my comments on the article. (In fact I dont even really agree with the main premise of the article...that Marcelo's success is just based on his love for bjj)
Of course we can love doing bjj without being the best in the world.
However, I think something that should not be discounted (just like Brent said we shouldnt overlook a champion's unique athleticism), is the amount of time these champions put into the mat.
I really think that if you train 35+ hours a week, for 5+ years, you will be super successful at BJJ. The Miyao brothers are the popular champs at the lower belts right now. These guys live on the mats (actually sleep on their academy mats). There looks to be nothing physically special about them- same can be said for many other champs.
IMO, if you take 1000 kids, aged 13 years old or so, and tell them they don't have to do anything except train for 35+ hours a week, for 5 years...I think maybe .5% of the people would stick to it.
Almost every academy has one of these kids- they train their asses off until around blue belt, and then without fail, they quit or cut way back on their bjj, as they get more involved with girls, school, work, life.
I think that is what factors the most in making a world champion...enduring the grind of training day in and day out, when nobody else is....for many years.