ZiPS uses a static called zWAR, or projected wins above replacement. Baseball reference breaks down how you come to this number. ZiPS has Kris Bryant at 6.9, which is the second best in baseball right behind Mike Trout. Anthony Rizzo (5.7) and Addison Russell (4.2) are also projected to have all-star seasons. This is fantastic news considering that these numbers will not account for players stepping up and performing better than expected, like so many did last year.
Unfortunately, ZiPS has the Cub's bullpen as the weakest part of the team. With the departure of Aroldis Chapman, the Cubs will mainly rely on Hector Rondon and Perdo Strop in high leverage situations. Those two have the potential to be solid relievers, but may never measure up to the all-star, record breaking caliber pitcher that is Aroldis Chapman.
The starting rotation, however, is looking pretty good. The only starting pitcher that the Cubs will be losing going into next season is their fifth starter Jason Hammel, who's zWAR is at 1.5. His spot may be filled by Mike Montgomery, who is at 1.1, but hasn't been tested as a consistent starter with the Cubs.
No matter what anyone or any calculated projection says, it is safe to say that we can look forward to fantastic Cubs baseball in 2017.