Except that none of that stuff about the talent is true ...
The GM signed the two top position players on the FA market knowing they would both provide below replacement level contribution for almost half the season
The GM traded for a 26 year old who had improved for 3 straight years with the assumption that he would regress as a 27 year old
The GM traded for a decent innings horse assuming ... well Miley has actually been roughly what was expected, a couple of flammable starts notwithstanding
Any reasonable projection of this rotation was to be something in the middle - not awful, not the 1995 Braves, just some guys (like the 1975 Reds) nobody will remember who won't kill you. And since the guys he acquired were young you can at least cross your fingers on more.
The talent part was not the issue - it has been the execution therein. I know Cherington is not perfect and do not absolve him for how it has gone, but his failing - if anything - has not been at the player level. Look at the Pawtucket and Greenville rosters for proof there.