I wouldn't say they have a lot of work to do, although they obviously will need to continually re-build their pitching staff. Their position player group is set up extremely well for the next 5 years. They have 2 clearly above average positional players and Contreras most likely makes 3. Russell hasn't shown much with the bat and his defense has slipped this year. Schwarber is a disaster and needs to be in the AL, Baez is toosly but makes a lot of dumb mistakes and isn't much of a hitter. Happ may join those ranks to make 4, too early to tell. They have nothing in the way of young pitching and are going to have to pray young guys get it really fast or keep cycling in free agents. There is no dynasty here, just a good team. If you had to rate teams with the top 25 and under talent in baseball I wouldn't put the Cubs at the top of the list.