Hiring is the easy part. Rampant scaling of engineers is easy to do, if you're not paying careful attention to quality, or you're dumping cash and or options/RSUs with the promise of riches (case in point: Uber sounds like they overhired and then imploded).

How successful was your hiring? What was the performance ratings of the people that you hired and how many met your expectations and how many didn't? What was the average tenure of those employees after this big hiring spurt? Those are the more interesting pieces of information.