I'm a big fan of Dare's writing, but on this one, I think he missed the mark wildly, for exactly the reason you cite: Google's research says almost the exact opposite of what he's claiming in this post.
With that said, the large variation in ratios of disadvantaged minority employment at big tech companies does seem meaningful (and he cites that wide variation). I think intern and HR pipeline variation is likely very relevant to this difference.
The problem is with his implication that throwing darts to pick from a pool of moderately qualified people would yield a reasonable result.
Both "they work" and "they don't work" are unsupportably broad. Google has substantially reworked their interviewing process on at least one occasion, producing a big change in results. Story here: http://www.nytimes.com/2013/06/20/business/in-head-hunting-b...
Meanwhile it's crucial and nigh-impossible to identify how much success is based on interview performance as opposed to selection effects in who interviews, and how interviewers see different candidates.
This is wrong. Apparently google has internally done much research and their interview techniques have strong collreation to success on the job.