I agree. I don't think there's anyone who thinks JF is the best manager in history or even a great manager. But to say he sucks and should be fired should be backed up by evidence that shows he is worse than many/most other managers. The onus is on those who want to argue this, given the status quo. To give examples of "boning away" games or other mistakes he's made is not that evidence, because we know that all managers make those same mistakes. So, there has to be some comparison between other managers and ours to show that he should go. In addition, who would replace him? And, what evidence is there that that guy would be better?
To be honest, I don't think this is a realistic task, since there is such a large amount of information we don't have. We have almost zero information on how he handles the clubhouse and his personal relationships with players, coaches, and the FO. We also don't know anything about what data/metrics/analysis the Sox use in advance scouting and JF uses to make decisions. That's two very large chunks of the manager's responsibility, imo, that we just can't judge. So, sure, we can criticize Farrell for many things (and rightly so), but it's a long climb for those criticisms to ever amount to the level of fireable offense, since I'm not privy to much of what he's responsible for. To my recollection, he hasn't cost them a playoff spot/series with his in-game decisions, he hasn't forced their hand into terrible, franchise-hamstringing personnel decisions, there hasn't been a chicken and beer level clubhouse fiasco, and he hasn't embarrassed the organization publicly. Admittedly, that's a pretty low bar. But without evidence showing he's below average at his job, why would you fire him?