Really good idea for this challenge. There seems to be quite a few compression artifacts or JPEG compression that is slightly distracting - esp. around the ball. I'm also wondering if maybe the lighting source is just a fraction too harsh because it's reflecting funny in teh metal. Maybe a reflector would have helped, but I'm not sure. GOod luck though.
I think the crop is too tight on top and the ceiling is a little distracting. I think the colors are fine, but the lighting is off (particularly on the ball). The photo is also off on the horizon line. You can see the rectangle behind the ball is not straight across. I would change the angle you shot from to help strenghten this photo I think.