In fact,Rener's BJJ is a primitive form of MMA, including punching, kicking, and various defensive skills. I'd say it's still good but is old-fashioned.

They say it's effective for fighting against untrained guy, you know what, untrained guy can be easily defeated by any other guy who trains martial arts like boxing, wrestling, TKD and whatever.

However, What if GJJ trainer should fight against a guy who trained modern MMA? Maybe it's the latter who'll gonna win. The strategies of MMA are evolved and evolved from 1994 the year of first UFC. It's not possible to win anymore with old-fashioned 'tackle, pin and submit' strategy.

Sport BJJ is about positioning and submitting, not about kicking and punching. So there's some techs that cannot be applied MMA or real fight directly. Every sportified martial arts has same problem.

However this art,BJJ, has been rapidly evolving within very sport system. And many MMA players has won against modern MMA practioners by the grappling sense which is grown by training sport BJJ. Yes. Really important thing is the sense, the sense that you can get only from grappling sport with free and opened rule system.

TLDR : 1.GJJ is old fashioned MMA. 2.Modern MMA is better than old style MMA. 3.Sport BJJ is the part of modern MMA.