Dev team and game-life/testing/balancing team are two different sets of people. The dev team develops the game mechanics and provides tools to the testing/balancing team, who's in charge of tweaking most of the parameters of the game mechanics.
Sundi is the leader of the game-life/testing/balancing team, not the dev team.
You can work as a developper on FFXI for years, and have no idea who AV is. Developpers are the people who would tell the community about why it would be so hard to switch to DirectX 9+ or revamp the UI. But 99.99% of the player-base just wouldn't understand what they're talking about.