Absolutely right there. I remember because we bought their captain when they were a tier 2 team that went up. They came down and up again. And now down. Maybe it's because from the first relegation, these teams retain the bulk of Prem players, perhaps?
Then when they go up again, they don't replace these players some of whom may no longer be of Prem standards, as such they struggle and come down. but this time the team is not as strong as the first relegation?

Obviously this happened with Forest in the 90s, but the 3rd relegation was the killer, we had crap players and Platt bought even worse crap and you know the history from thereon.

Of course not every single relegated club goes back up immediately. I don't think there has ever been a case where all 3 came back straight again, is there? But usually 1 of them does, and 1 of the remainder in the parachute system (pure conjecture here).

That said we certainly don't want the likes of Newcastle, Southampton, Stoke and Watford here next season.