I think next year sportsbet have to find a new team for cooperation.
They don't have to. The boys just had a bad day and there are more games to come for them so why be discouraged with one match?
This happens for most teams, there are times that you really can see something unexpected. But that's it and it's already done so move on to the next match.

Yeah. Watford has their highest ever finish in the league and it is a good team structurally.
They just had a bad day, they are low on confidence with no wins yet, and City were wounded from Norwich (who lost to Burnley!). Remember Chelsea had a bad day also last season on this exact meetup. Don't give up yet Sportsbet, this is just the way things happen in football. Move on, win the next game, one game at a time.