[smartician]

It may have something to do with the transition from "old" to "new" Admob. Advertisers can request refunds for unused funds from the "old" Admob, maybe that job had a bug and refunded everything. Makes you wonder how that's possible for a company that has the supposedly brightest of the best developers.

[adventured]

I wonder if there is much of a difference in engineering talent between the advertising products (AdSense, AdWords, Admob, etc) side of Google compared to the consumer and business product divisions (search, maps, G+, docs, etc) and data center engineering.

[peterjancelis]

If anything I would expect the ad related engineers to be more talented, given that it ads are the bread and butter of Google's business.

[robk]

The talent is the same caliber across the board with the only exception possibly being new acquisitions.

[jrochkind1]

The smartest people can still make mistakes.