If the ATA is long then the brace height has to be lower. And how was the peak weight of the bow. It certainly changed also. Most likely it's a lot less. When measuring strings and cables off the bow (not under stress) they will measure about 1/2" shorter than specs.

But the one thing about twisting rigging is that if you only twist the cable all you are doing is back-rollong the cam, increasing the drawlength, and increasing the weight in the process. To get the ATA you desire you have to twist both the string and the cable while trying to maintain the proper drawlength. But as gibblet said, 1/2" in ATA is quite a bunch.

And how do you know the ATA is long? Did you actually measure it when the bow was fairly new? You can't rely on measurements with old rigging on them. This stuff has stretched out. OR are you using factory specs? These often vary from bow to bow and are not absolute values but guidelines to follow.