Reversion to the mean. They were never that good. Before the start they were predicted to finish around 14th position. Even while they piled up wins, stats like xG showed a different story. It was a house of cards. A similar squad finished 11th last season.
But still, the collapse is even more impressive than the unexpected good run before that.
Our clubs are so poorly managed that we think RB can set a good example on how to do things correctly. We don't really care about they being an artificial team, we have more important issues to deal with, like very bad football pitches.