Yes he drives play and adds to the offense. Being a good offensive defenseman is ultimately supposed to help +/- too. Severson contributes a lot more offense than anyone else on D and yet his plus-minus is way behind anyone else's on D. I'm astounded that people don't see an issue with this. If Severson made a Merrill-type middling contribution offensively his bad +/- would be even worse.
It's just the puck not bouncing right, that's all. I'm sure it happened to Scott Niedermayer one year too. Not that I'm comparing Severson to Niedermayer, but these things happen in the course of a career.
Here's just a helpful test. Severson right now has a 5.4% on-ice shooting percentage. That ranks 121st out of 126th in the NHL among D with a minimum of 750 minutes. Noted terrible offensive D Torey Krug and Shayne Gostisbehere are below him.
How many D have lower than that over the last 2 years time and a minimum of 1500 minutes?
Zero. I was going to repeat the test until we got to zero, but we're already there at just 2 years out.
What's the lowest a D has over 5 years and a minimum of 4000 minutes?
5.95%.
And Tri citing 5-on-5 plus minus is selective stat use. I understand taking out empty net goals but you can't take out 5-on-4 goals against. That would be like taking out PP points when comparing Sevs to anyone else offensively. Sevs is supposed to help the PP, not be part of SH goals allowed.
I'm not sure why this needs me to explain it - I don't really care about PP points. I care about a functioning power play in general, but whoever gets points on it isn't that important. A player can get a lot of PP points and still be bad for a power play. Likewise I think a player can seldom get points and be good for it. You will almost never see me combining even strength and power play anything at the NHL level. So no, I don't care much about Severson's 5 on 4 +/- demerits.