There are off nights and good nights. You cannot blame a player if they will suck one night but play good in 50 games. Not the coach, too.
Everything must be considered when a team we bet on suddenly loses, even if they are the heavy favorite to win the game. Their opponents, for example. If there's rivalry and if they have a history of losing to that team, we must check that out.

But when we are just talking about a team that failed to be good in a season, that's a different story. It could be the management who are trying to be cheap by signing up players that ain't good enough and just want to keep their team in the league for different purposes.