Hi,
After several locking of blender, hours of frustration and even a Blue Screen Of Death … I finally managed to have an acceptable result, Yay 
I reduced the football size to match a real one, and added players !
Players … Well, it was those players that caused my computer to have issues: First they were a little too high poly (So I created quick T-shirts and Shorts quite low poly and deleted body parts) , then the shader (skin) used Subsurface Scattering = a lot of processing. Even with that out of the way, the particle system (hairs) was quite heavy too, but I managed to keep it 
Those players originally use the body I made in order to practice anatomical modeling:
Oh … I see something coming behind those mountains:
Click to show
HI THERE! WHAT ARE YOU DOING ?
This section is interesting but I would say it is pretty difficult to make something that blend well with the background and I didn’t master that art yet 
Cheers !