I haven't seen Spartan since I saw it in theatres, so my mind is a little fuzzy on details, but if anything, Mamet's usually convoluted plots just make sense in a movie about secret government spies/assasins.

My main beef with Redbelt has to do with plot points. Spoilers folow, so anyone not having seen the movie please skip this post.

-The whole plot jumble of a big conspiracy involving cops, a washed up Hollywood actor, MMA promoters et al just to steal something from a BJJ instructor seemed silly.
-The fact that all these already unlikely events occured to steal an IDEA from a BJJ instructor, to use in some budget PPV scheme seems both silly and trite to me.
-That the "idea" is a way to handicap fighters at "random" by picking coloured balls seems even more dumb to me, given that you could never handicap legal fights to begin with (if said fights were underground or something, sure, but the movie goes out of its way to make it seem like it's all legit TV PPV UFC style event).
-If they wanted to handicap fights, and ignoring the fact that they couldn't legally/realistically, why not just make up some BS thing? Draw straws? Random computer generated results? Nope. You have to steal some budget idea from a nobody BJJ instructor which involves a series of complex and highly unlikely occuring events just to get the idea...
-Oh yeah, you need a MAGICIAN to help you fix the marble draw

I liked the characters introduced in the movie, it started out really well. I'm a Mamet fan, and an MMA fan, so I had high hopes for this movie. But the series of what I consider to be increasingly dumb and unneccesary plot twists, ending with what seemed like a lame Rocky rip-off ending left me with a bad taste in my mouth, which ruined the movie for me. Maybe my hopes were too high? Maybe my liking of MMA as a real sport meant seeing it portrayed so poorly and stupidly just coloured my own view of the movie. Not sure.

Anyway, end rant. I'm coming off sounding way too negative here. haha.