The fact is that Kane does not play defense in the D zone at all. Sometimes he'll do a little neutral zone back check, but that is as far as his defensive engagement goes.
I love to watch him on the PP, but he is largely a PP/OT specialist now. If you give him time and space in the other teams D zone, watch out. In a tight checking game and for most of 5 on 5 play he is a major defensive liability.
So with that said I don't think it is that the entire team plays different without him, I just think any line with him and DBC on it is a massive challenge on defense for this team. God forbid they end up out there with the 3rd pair. While I think DBC tries really hard defensively he just isn't someone who is super effective against the forecheck. This goes double for Kane, who is clearly out there trying not to jack up his hip further to some extent. I think they should always try to be paired with Ed/Aljo because that is our least panic defensive pair.
So what you see when he is gone is more defensively balanced top 6 without him. If the Wings had more smart players we'd be better off trying to get Kane like 3rd line matchups, but we only have 3 guys that mesh with him offensively. He's sort of like Datsyuk in that regard. Datsyuk and Kane think the game at such a high level that you need at least 1 other player with a high offensive IQ for them to be at their most effective. Maybe him and Soder could be a matchup pairing. None of our bottom 6 outside of Berg (same issue as DBC though) have the smarts to play with him.
The Wings are in a weird spot where they need his offense because we lack scorers but its a double edged sword because he definitely increases their chances of being scored on too. When he is out there helping your PP rock out at 30-50% then its worth it. If the PP struggles though then his offense probably does not make up for the defensive liability.
From an entertainment factor I love watching him play, but as I noted last year too I don't know if he is the best fit from a winning perspective.