I believe we didn´t made ruby for 2 reasons who worked together:
i.) Frags: In the last event people took the oportunity to fill their frags reserves. The event was a sucess mostly because of this.
When this event came out only those who use a lot of instant finishes needed more frags. So, many didn´t saw this event as an oportunity to fill frag reserves - already full - and didn´t participate;
ii.) Rewards: 30 days ago we got 3 chests with Con500, DB1500, AM500, AL500, Lib500, LF1500. Now we were being offered 3 chests with AL500 + AM500.
Overkill 1000 is amazing, but is not one of those buffs that makes people jump out of chair. Same said for necrosis and holy flame, specially nowadays that there are so many ways of increasing your damage. Sacrice, personaly only use it in 2x events.
Considering the above, the current rewards were less appealing then the previous ones.
I know on the long run all the frags we can store is great and I know all the epic pots we can get are a great advantage, but many people only think on the present day.
People had the frags storage full and they had better pots in their BP so they either skip participating, or have done only the minimal 5k.