Why second-rate ships of the line were less prominent

Why do first- and third-rate ships appear more often in naval history than second rates?

Third rates were the economical fleet workhorses and first rates the powerful flagships; second rates filled a narrower middle role and were often hidden within larger fleets.

By analogy, third rates resemble efficient heavy cruisers, first rates the leading battleships, and second rates a category between them, similar to battlecruisers. Second rates cost more to build and operate than the fleet's workhorses without matching a first rate's prestige and firepower. They still made sense for particular duties and distant stations, but were often overshadowed inside the main fleet.