Barriss has a very low damage. Even if your basic skill level is 8. The critics do not pass it 2,5k. But in my opinion, this is intentional. Barriss has the potential to provide sustainability for the whole team, especially if she is the leader. His healing skill is the best in the game, not to mention that she is absurdly tough.
But the truth is: This skill package is great for GW, which is a game mode that depends on sustainability. In the arena it does not work. The battle in arena lasts just a few minutes and the first/second rounds are crucial for victory. The fights simply do not last long enough so that a healer can make a difference. It is precisely why little by little healers were disappearing from the arena. On my server, there is only one team that uses Luminara as a leader because it is a team with 5 Jedis.
I had a recent experience fighting against this Jedi team that used Barriss. 37k power: Luminara (L), Yoda, Barriss, QGJ and Aayla. I destroyed them like a wrecking ball. Had 2 healers, so what? They died the same way.
In my view, the game has heroes who shine in the right places, not everywhere.