Arsenal group is a joke compared to the other groups.
4 Liverpool it will be very hard to get through; Chelsea is better then last year and Betis got some very good brasiliens.
United and Villareal should get through in the other group, but Benfica and Lille are both good teams, who are better then every rival Arsenal got.
Rules are simple anyhow to win the CL you have to be better than all the other teams anyway like Liverpool proved last year, who would have predicted that at the start.