If Dps aren't meeting DPS checks, they need to be told or replaced. They either learn or they don't. You can be nice about it though, but clear communication needs to be there and if they can't deal with the fact their not meeting a dps standard set by SE. Kick 'em and let them pay for a carry.

Tanks should never lose hate if their gear is around the same level as dps and healers. The only time they really could is at a pull and even then, tanks have the ability to quickly pull back the mobs and establish hate.

Finally Duty finder is for learning groups now IMO. You're randomly placed with 7 people that -may- or -may not- know the fight. It takes a group vote to kick them out and if you leave you take a 30 minute hit before getting a chance to re-attempt. How anyone can think of those conditions as a farm or clear party. I have no idea.