I have a hard time determining how much fault Jed deserves for the pitching. Yes he absolutely expected to have Horton all season and Steele half the season. He didn't know yet that Brown would show TOR caliber performance but expected him to be available all year. If you add them to the pitching options you have Steele, Horton, Brown, Imanaga, Boyd, Taillon, Cabrera, Assad, Wicks and Rea as starting options. Cabrera hasn't worked out, that's on Jed for making the move, Assad, Wicks and Rea were fringe rotation options at best. Taillon fell off a cliff. But there was depth there theoretically.
Conversely when you were relying on a player returning from TJS, a young pitcher with a history littered with injuries, a pitcher who missed half of the previous season with a mysterious neck injury that you were never able to fully diagnose, you are introducing a ton of risk, and that risk blew up in the worst way possible.
In terms of the pen, people say that Jed avoided spending on the pen but he actually did spend a bit more in FA than he normally does on RPs. He may have identified the wrong ones but giving $20m to Maton, $13m to Harvey, $10m to Thielbar, $4m to Webb, is not nothing. The problem is that Maton and Harvey got hurt most of the season, Thielbar fell off a cliff, Webb was good until he was not. But also in general they all fit the same pitching mold that seems outdated in philosophy.
Bottom line Jed needs to take a long look in the mirror this offseason and work on overhauling the organization's pitching philosophy IMO. I'm not an expert on pitching, but its noticeable watching other teams and then watching the Cubs that we're definitely doing something different, and the results (not just this season but the last few seasons) suggest that our approach is wrong.