Kinda jumping around on sides here, but the positive regression you'd expect is, in my opinion, going to be pretty offset by the fact that Steele and Shota aren't here. Horton is exciting but the track record of other top pitching prospects their first time up is not encouraging, Colin Rea is Colin Rea, we're one injury to the most injury prone dude in baseball away from Jameson Taillon being our ace for the near term future.
Basically, in my mind: the offense is very good, PCA, Busch, and Nico are slightly outperforming their xwOBA but PCA and Busch even with a little regression are still elite players. Tucker, Dansby, Happ, Suzuki are all underperforming and have already been fine to great. Catchers are fine. The bullpen is bad, but all the talk around here that the Cubs are in this unique situation where we need to be nervous about close and late situations but everyone else is just nails is very over the top. The rotation is kinda shaping up to be a disaster, some part of that bad injury luck, some part of it self inflicted, a lot of which can be solved in an expensive way, and with knock on effects that would ease the bullpen problems. Go pay for a starter or two, as soon as possible.