They will not be able to achieve it. Winning the treble last season was unexpected for them at the beginning of the season, they did not expect things to go so well for them until the end of the season, that they were able to outplay other teams that they played against in all competitions. Some of the major players that contributed to this success are no longer in the team, so it is not just going to be a replay of last season especially also with how prepared other managers in the premier league are looking ahead of the start of the competition. Manchester City will face a tougher opposition this time.