I think there's something about the ground mechanic that I'm just not getting.
I was doing a basic exploration mission against Rommies and I kept dying on the boss pack. After about five tries I just gave up.
After the third try, I left and spent every EC and DL I had on better gear for my BOffs and it didn't seem to help any.
I tried everything I could think of, CCs, kiting, using all my buff/def cooldowns, but I just kept getting overwhelmed by the Engineers and all their gadgets. Even when using BOff focus fire on my target, I couldn't seem to burn them down fast enough because the Medics would heal them. If I went after the medics first, the engineers would get up their gadgets and overwhelm me.
The CCs just don't seem to last long enough to be very useful. Which is strange because the ship CCs are excellent.