This is a great post, and it's an area we can improve upon without major financial investments.
I'm not usually one to suggest rebuilding the bottom of the roster. I normally suggest building from the top, and through attrition the other players move down slot by slot until all the deadweight players are replaced by mediocre ones- not other replacement level players (or worse).
One hope with Bloom was that he could find these gems, at low costs. He's not perfect in this area, and sometimes through quantity signings, you end up with a few that stick and suffer through the trial and error process as some, like those on your list, fail miserably.
Hopefully, next season's bottom feeders will be at a much higher level that we saw, this year and even some in 2019.
Here are the ERA- for all 25 Sox pitchers with 20+ IP from 2019-2010:
202 Shawaryn
176 Godley
153 Springs
129 Cashner
125 Johnson
120 Josh Smith
114 Porcello
113 Velazquez
106 Eovaldi
104 Mazza
100 Weber
97 Perez, Walden & Brewer
96 Brasier
91 Sale
89 Price
88 Hembree
83 Taylor
82 D Hern & Barnes
80 Lakins
79 ERod
71 Valdez
43 Workman