I've been down on defense Array before, but I am finding you can flank, it just requires an armor boost and/or a little cover fire.
Here's my strategy to break up a formation on defense array. Once people adapt this will probably fall apart, but for now, I find it can knock a team off balance pretty easily.
1. Post up on the high ground near the shield wall. Check the scene,
2. If someone is camping their high ground see if you can take them out, if you can't get a shot, see if you can get a teamate to pin them down.
3. Point at the opposite teams hill base, even if it's occupied.
4. As soon as you are in the air, turn, and mash defense/speed boost as soon as you get clear of the elctiric wall, doge like crazy. If their high point is defended, head to their upside down cover, and try to flip to the covered side as soon as you get there. If there's a swam guy all by his lonesim, head right for him, he can't do shit if you charge him.
5. Swing around behind the other team and pick up 2 or 3 easy kills and break up their position.
Even if you don't make it, I find their entire team seems to focus on you, allowing your team to pop off at least one quick kill, or reclaim the hill.