Our first win - a long time ago, i can't remember which season - was with a zone defense. So it's at best the second time.
It takes me back to when I was pitching it the first time around to the player builders in my org and got some really negative feedback. I totally admitted that it might not work, but most of the attempts at making a zone defense had generally been made by second-tier DCs as a way to find a way into the top, not by a top-tier DC who already knew how to play good GLB defense who wanted to try something new. When I was recruiting on our sister team's forum I was told that it had been tried before and had failed every time and nothing would be different this time. I'm not usually a bitter person but I couldn't help but pop into that forum and update that thread from time to time with one line posts like "Made World League!" and "Made world league playoffs!" and "Won World League Championship!" I'm generally a higher road type of guy but I'm also only human.

I still don't know that it's "better" than a man defense but it's very different and certainly has its strengths, and I was just so burned out on running more or less the same defense for years that it's been nice to mix it up a little!