In the very first playoff the DEVAS won the cup, which happened to contain SOMA, the booze of immortality. The ASURAS have tried without success to snatch it back ever since.
The good thing about SOMA is the DEVAS don’t have to worry about foul play, unsporting behavior and pitch injuries, whereas the Asuras can be taken out of the game never to return.
So to field a full team the ASURAS have to spawn in cracks and crevices, and have their evil ways with whatever they can, be it man, maid or monster. Every now and then they manage to sneak in a goal and win a sip of Soma, which is such a great restorative.