Andreesen Horowitz is loosing the
ability to identify impactful startups
Pet peeve: it's losing, not "loosing".
I don't know if anyone can properly guess if a consumer startup is going to get traction until it does, especially in the mobile space. That said, they did manage to get a 312x return on their seed investment in Instagram (which they declined to invest in a second time as explained here: http://bhorowitz.com/2012/04/22/instagram/)
A-H offers seed investments to YC companies in order to get a foot in the door with the small fraction who will succeed. Offering blanket seed investments confirms that they really don't have any idea at first either. There's nothing wrong with that, it's just the nature of the beast. (http://venturebeat.com/2011/10/14/andreessen-horowitz-to-giv...)
I don't know if anyone can properly guess if a consumer startup is going to get traction until it does
A classic example is the drug Viagra, one of the most profitable consumer technology investments in recent history. Its (most profitable) use today was originall reported as a "side-effect" in early clinical trials.