If it's truly CAB (Certified Angus Beef) and it's listed as such then it's a Marketing answer.
There is a Angus association and they have strict criteria for what is/isn't CAB.
I'd buy it and try it. It's usually more consistent.
Me, I won't say they're the 10 XX% of all briskets, that % is just something their marketing group spits out.
BUT, look for CAB not just Angus. Lot of people think they're the same and they are not.