Yes, fair point. EN goals shouldn't count towards plus/minus but they do. And that's hurt Lohrei disproportionately.
But even at 5v5 Mason is -8, which is still worst amongst the Bruins defenders. Peeke is next with -5. Hampus is best with +4. So not so bad, but still lagging at the bottom. And that checks out all along the line. In every major on ice stat, Lohrei has the worst or near-worst numbers on the team. One isolated figure you can dismiss, but when they're pretty much all pointing in the same direction they're probably telling you something. He's not miles worse than anyone else, but he is an outlier.
As to plus/minus more broadly, I do think it's useful, to a point, especially in comparing players on the same team and more so for defenders than forwards. I think it tells you very little for any one game, but over a span of 20+ it starts to become instructive. You need to view it in context and in the round, like everything else, and be aware of possible factors that might be unfairly skewing it this way or that, like the EN goals you mentioned. But with those caveats, I think it can be a guide to relative performance.
Essentially I don't think it's dumb or useless, nor is it everything or hugely meaningful. It's just one more piece of the analytical puzzle.
And just to reiterate, despite this critique I'd prefer the Bruins stick with Lohrei. Work in progress and I still believe in the upside.
