The Devils' current +/- is a fairly accurate description of the quality of play from each player relative to other Devils.
T, by your own admission "We all know they are having quite a bizarre season"
Which means stats, including +/- are going to deviate from what you see typically. You should not use an anomaly as an example to make your argument. Do the same analysis for say 10 teams and I'll bet your "difference" column won't look so off.