That's what the article goes on to describe, yes. Declining crime rates mean fewer new prisoners, but high recidivism rates plus long sentences means many old p

That's what the article goes on to describe, yes. Declining crime rates mean fewer new prisoners, but high recidivism rates plus long sentences means many old prisoners are still in prison. As those old prisoners die off or for whatever reason don't commit more crimes after release, the total population declines.