Going into the season you had 2 injury prone starters in your rotation in Sale and Eovaldi, then you sign 2 more starters with an injury history in Hill and Wacha ( he has been excellent) , Bloom set up the sox with a high chance of getting the injury bug in the rotation, which has transpired.
The back up starters from triple A have had some good moments in the rotation, but have been asked to handle way too many starts due to injuries which has caught up with them.