While Koji has done an admirable job for us over the years, he is now old enough such that he probably cannot stand up to the rigors of a season or even a short period. I hope he retires for the sake of his own reputation as he will probably be ineffective. Tazawa has been overused and appears to have a tired arm late in the season. He still probably can be effective but if resigned should be used less frequently. Could we afford for one of our 7 relief pitches to be shielded in that way? Ziegler is still effective but he is a FA himself and is 38. I would hate to invest a lot in $ and years at his age.
Our 7 BP pitchers will include Kimbrel, Robbie Ross and probably Kelly and Abad. Beyond that, there are quite a few internal possibilities, but no givens that can be said to be locks. Moonslav put out a nice list of possibles. My guess is we go after at least two as upgrades to the staff, one being a long reliever. Buchholt is in the running for that and as a backup starter, but the FO needs to keep an open mind going forward.
I also would be reluctant to trade Swihart, instead, I would look for a home for him on the team.