If i may have few suggestions:
1. It seems there are two rounds on same map before map its changed. Can you change
map after one round instead of two(same as other regular 1000 ticket FG server)?
2. 1000 tickets seems to be too much when there is few players(even when half
full), can you change it to let say 750 or even 500(i would try 750 first). This
can be increase to 1000 tickets again when server is running full later on.
3. Maybe exclude death walley map from rotation, it seems its least popular map
amongst players(although i quite like it even with that rubbish blue filter because
its different visual style). However i would wait with exluding this map for later
on.
Try this for one week and if no succes scrap it

If this doesnt work try other option: rotating 2 most favorite maps: Armored shield
and Alborz Mountains for another week.