Are you spreading out for defile ?
We originally had a couple of issues with the defiles and found that making sure everyone was spread for them was the easiest way to deal with them while people get used to the mechanic of escaping from them, there is only the tricky point of the 2nd defile/valk timer being close together that spreading may not be the easiest way to get used to the mechanic, once people are used to dealing with it then the need to get everyone spread out becomes less (melee especially) as the defiles are dealt with more efficiently.
A couple of tips given by other forum members that we used to make this easier, was to have one person always calling the defile timers so people knew when to spread (also calling valk timers as well), I believe dbm enables chat bubbles that say defile on me and warns if it is on you or near you in plenty of time to get away from it.
I would also like to point you to this thread where the good folk on here gave me a hell a lot of decent advice on dealing with fight mechanics from first attempts up until our kill
Hope some of this is of help and gl