Igor Actually, you make a good point. I do find that people stay near the top, but what I've seen is that they stay near the top more when all of the conveyors go fast towards the end of the round. When the conveyors go slow at the beginning, (at least for me) there's more fighting near the middle of the play area as people feel more safe due to the lower speeds.
But, that's the problem I have with this map. While I still find it fun, once all conveyors speed up a bit, the amount of fighting reduces to almost 0% because you're then just focused on staying alive. When the conveyors move really fast then you just don't have time for anything else!
This is one level where I'm glad there's a timer also, as if I get knocked out early (often happens) it's a long wait watching everyone roll and not fight. I find it hard to do anything useful even as a spectator on this one too.
I've not played it enough to find some tricks on this one yet. I'll keep practising!