>Testing the waters outside your specialty when you're in your second postdoc is not a bad idea. Presumably that means you've not been able to get a permanent job at least a couple times.

So while this might seem logical from an outside perspective, two postdocs are common if not pretty much the norm for people hired as Tenure Track faculty at high ranking institutions in many fields nowadays. The name of the game is derisking - how much of a track record can you build before they hire you to confirm you will succeed.