I'm wondering if their focus fire is just too much. Was it gear, practice, or just not a survivable combo?
yes

i'm not an arena guru, but you'll never be able to do enough damage that their healer can't easily heal through. Fears will eat you alive (can't heal the toon being focused), and even if you do, you'll run out of mana healing your group long before he will.

In BG's, you're not focused for long periods of time as much as arena - and your HPS on a focused team member at the front of the pack is just awesome - unless someone can kill them in 1 global, they're invincible - and they will love you for it.