Is it his outstanding shooting percentage? It's funny how the statisticians will use their nerdy numbers to explain why a player can be good but have no points like Shore yet when you use their numbers against them they come back with "shut down defensemen". How do you prove that exactly? Who is he shutting down? When the Kings are losing game after game and not scoring goals is his "shut down" game still evident or is that in wins? Is he shutting down the offense as well? Would he have more points if his CORSI rating was adjusted so that his average TOI was elevated in the offensive zone with the properly matched up players against the other teams 4th line?
I've got a lot of simple answers here for you but I guarantee you won't like to hear them.
"Defensive role" easy to prove with shot and goal differentials when they're on the ice despite starting the majority of their time vs top competition on hard spots on the ice (Forbort, notably, has struggled with this lately though, which is why you don't see him being defended right now--but he did before and the stats exist whether you like them or not). Regehr, Mitchell had similar numbers to Forbort (for role comparison, not at all saying Forbort is either of those two).
Shutting down hard competition is easy to see with Quality of Competition stats, especially when you compare team-internally. If you're consistently seeing top-3-6 ToI QoC, you're facing top players more often than not.
No, when Forbort is struggling, we're likely struggling. When Shore is struggling, not as much, but yeah, we're likely struggling. But I don't know what you're trying to prove here, it's like complaining "oh, are we winning when Kopitar isn't scoring?" When players aren't playing to their strengths throughout the lineup, we lose. We're not that good that anyone can take nights off, don't need stats for that.
Shore might have more points in an offensive role but there's nothing predictive about his current stats that would suggest that but I realize that last point is simply a biased tongue-in-cheek mockery by someone who rails against them because they don't understand them or the idea that some folks aren't so binary that it's stats-no stats. It's a lot easier to listen when your fingers are removed from your ears, and you might even learn something, even if you just disagree with it and would like to debate it.
This is all, though, just a thinly-veiled complaint about the raw production of our bottom players which has been demonstrated time and time again as a fallacy.