This ain't the development league. Devers is 20 in his first MLB and not even his rookie year. This is September, not April.
The 8 dingers are both real and significant,just as you say. But they were all in his first 20 games. In the next 16 he has 0 dingers and 2 doubles. Plus we are all watching his every at bat, which tell me that he has yet to adjust to what opposing pitchers are throwing.
You make a good point that leaving Devers in the lineup, even when he isn't hitting, won't make that much difference given the rest of the lineup, but you are also forgetting that his defense ain't helping either. He has 7 errors in 34 games and a DWAR of 0.
For all those reasons--pennant race, Yankees on our tail, 23 games left, struggles at the plate, age 20 in first MLB season, doubtful defense--I give Farrell on pass on whatever he does. I honestly think Devers will get back in there precisely because of that stupendous hitting talent. But I am not quite ready to throw Farrell into managerial purgatory because he is mishandling Devers.
1 Nunez 2b
2 Pedroia DH
3 Benintendi LF
4 Betts RF
5 Moreland 1B
6 Bogaerts SS
7 Devers 3b
8 Leon C
9 JBJ CF
Pedroia for HanRam at DH a small surprise, but I thought Pedey looked better at the plate last night. Devers, honestly, is no surprise with Pedroia at DH. He might be in a slump or struggling to make adustments, but we flat know he can hit. And we can be pretty sure that Lin, Marrero, Holt, et al, can't. (I cite those three under the assumption that Nunez is fine at 2b or 3b which would allow any of those 3 to play 2b).
Devers a little problematic fielding at 3b, Nunez going back on popups ditto (but now he has JBJ and Betts backing him up). Bogie only so-so at SS. But Devers was at 3b for Fister's last, superb start. Nunez played SS and 2b. Pedey started at 2b. IF should be OK if not sterling.
I sure don't believe that. They are losing because they can't hit. Moonslav has documented that most everyone has a worse OPS this year than last and the second half vs. the first half of this season. I completely buy the idea that their attitude is just fine.
NOAA map shows a lot of stuff on top of eastern Massachusetts (Boston included) and more coming from eastern and central NY state. 50% might be optimistic, but local weather guys are probably pretty good.