Long ago, when Football Outsiders was still in its infancy and football was less sophisticated generally, one of the best indicators that a team would bounce back (or crash down) was in the difference between their DVOA on 3rd down vs. 1st and 2nd down. In theory, teams should perform about as well regardless of down, but because 3rd down is higher leverage by its nature, random struggles or success there could drive a team’s entire performance.
Football Outsiders has been around a long time and a lot has changed since then. With more specialization and sub packages, third down is now a fundamentally different down than the rest.