I have no idea what they're doing with him at the moment. They've completely forgotten the DB vs The Authority thing, leaving him messing about with Kane, who was only recently retired? Although Steph does keep sticking her nose into it for whatever reason. Why bring Kane back, straight into the title picture, when there are so many other options available.
I think HHH got a massive hard-on at the thought of bringing Evolution back (plus Batista's general comeback fail), so he put them straight into a feud with the Shield. Personally I'd have let DB go through every member of Evolution, one by one in successive pay-per-views, building him over a longer period into a viable Champion. Once he's got through all of them, you could make him face all 3 in a handicap and take the title away from him, keeping the crowd behind him, or someone could interfere in the match, giving DB the win and allowing Evolution to move onto a new target. DB would then move on to someone else.
Also, slightly off-topic, but Brie has the worst "I'm really, really scared" scream I've heard in a long time. This week's Raw was laughable when she was trapped in the car with Kane, she's just shrieking as long and loud as possible. I wonder if she's like that in bed...