+/- is more of an overall stat than it is a defensive stat. It's hard to be a plus player when you score as little as Shore does. He is not awful defensively, but I think his overall play this year has been extremely disappointing.
The offense needs to be more frequent. I completely agree.
Stylistically it's going to be a drag for a pass first player playing with guys like Lewis and Brown. Which by the way, statistically speaking was one of the most threatening lines the Kings had this season....they just could never finish the puck.
Dowd is going to run into the same problem playing on the Kings bottom lines.
Richards did. Stoll did. Both were what you could consider "Pass first" centers. Playing on the Kings bottom six is not a recipe for high end production by any means. That has to be considered a little bit. That being said, Shore probably would have 4-5 more goals and about 4-5 more assists this year if not for things like...flubbing a shot, a rolling puck, or losing handle on it at a key moment.
Overall though, I'd say his strides defensively are very good, but it is not going not going to stop most critics who expect offense regularly. That's just me though. I like Shore's game personally and think he is a fine bottom six center. I can definitely agree with a desire for more offense, but a good defensive center is fiiiine by me.