Good work here. It would probably be best to not do the black and red split image. There is another popular MMA site with a similar logo. Also, there should be two fighters and emphasis on the Z. I would like to see more of your ideas with those changes.
You are doing very well with the concept. I like the black lettering. Can you make the Z red and for the slogan use :FOR THOZE WHO ROLL. Also, the round emblem is better than the square I think. The fighter need and opponent and they should be in the act of "rolling" or ground fighting.
Great work on #35 and #34. We are getting closer to a solution. I will be ranking these highly once I get home. I'm working off my phone right now. The fighters look awesome but there is no striking in jiu jitzu competitions. They need to be engaged in a grappling match... Maybe one guy choking or doing an arm lock on his opponent.