How did "they" kill the series?
They weren't pointless fillers. Those fillers were made to put some distance between the anime and manga material.
The fact that they "killed" the series is my own personal opinion. The plot just seems to be spiraling downward and when I compare some of the earlier chapters to the new ones, it seems so rushed and not as well thought out.
While I understand that they had a reason to be there, fillers get annoying after a while and one has to wonder if so many were necessary. But other than that, I can't really say anything about the anime. I don't watch it.