I like the variations in the logo at the top of the pages. Yeah, the quality in lighting of the fighter photos is pretty bad in some of them. Maybe you can create some edge effects with different layering or lighting effects to make up for that or make the fighters 2d layers in a 3d space to have them lifting off of the poster.
If you are looking for new ideas, probably my favorite poster-design company recently is a company that a Chicago-based club called The Underground is using for their promotions. They are Rockit Ranch Productions. Here's a
link to their poster gallery. Not all of their designs will apply to what you are doing, but they seem to always have a theme for the poster or the event that is reinforced heavily in the typeface they are using and the overall layout.
I would also say that if you are looking to try something different, see what it would look like to make the faces of the fighters fill the poster more. Right now, you are showing their bodies a lot, but I already assume they have good bodies if they are professional fighters. What I'd more want to see, as a viewer (not a promoter), is the intensity of the facial expressions. Maybe if you are only placing two fighter's faces on the poster, try doing a split screen with one half of one face on the left and one half of the other face on the right. It would be more visually grabbing for me. Then, very small in the background, you could have the full figure pose if you are required to put that in there.
I would also work more closely with the photographer to take shots which will match the lighting in the layout you want to do. Like in the last poster you display in your post, there's a specific light source in the lettering. If you could match this light source and color in the original photography, that would be ideal. Otherwise, I'd use Photoshop's lighting tools to try and mimic that light source on the fighters. I hope that makes sense.
