It's on ownership to find a better-than-Farrell level manager. They exist - Francona wasn't hatched out of an egg, but few thought he was the obvious choice before he was hired. But at this point, even an equal-to-Farrell level manager would send a message, provide new faces, and change the path of the team.
They just have to avoid a BV and they're likely to get a net gain, either by a new manager and staff coaching out better performances from the native talent, or by picking a better in-game manager who can use less robust performances in a more optimal way. Louvello's not perfect, but imagine him managing a team with the 2016 stats of all of the players? I think the outcome is likely better if he would have had the sense to rest key players and/or use them for the post season.
For all my tongue in cheek upthread railing against Farrell, he did do a better job with the bullpen this year. But the underperformance of the players is on him as well. Let's look:
The 2017 team saw regression for all batters (except Devers and Vaz). That should not have happened. Even in a bad luck year.