Minus-30.
It’s a number that serves as a lightning rod for all of Jeff Petry’s detractors and an annoyance that won’t go away for the defenceman’s supporters. It’s a number that can’t be hand-waved with “oh, it’s just plus/minus” because there is so much separation between Petry’s -30 in 2017-18 and the -11 of the defenceman with the second-worst plus/minus value on the team, Joe Morrow. When one factors in defence partner Karl Alzner’s -7, Petry is shone in an even more negative light.
But there are reasons for Petry’s plus/minus, and these reasons have more to do with the defenceman’s circumstances than his ability.