When you consider the overall scoring trend in the league it's just that much more impressive. What a player.
Also it's not like Ottawa is some sort of offensive juggernaut either.
We're 5th in the league in goals for. He's been on the ice for 109 goals forced this year (all situations). The Senators have scored 199 goals this year. That means he's on the ice for 54.7% of their goals for while only playing 48.5% of the minutes (at 29:07 TOI/g - obviously the word "only" in that last sentence is relative).
Take away the goals EK65 had the goal or primary assist on (let's pretend those second assists aren't as important) and we'd be 29th in the league, ahead of only New Jersey, and behind even the Toronto Marlies.
Let's pretend we replaced EK65 with another decent but not outstanding offensive defenseman, and that guy replaced 70% of Karlsson's on-ice production. (a generous amount, imo)
The senators would have scored 175 goals, tied with Columbus for the 22nd least in the league, and would probably have even more goals scored against us, as Karlsson despite the haters is pretty good in his zone.
We would have a GF/GA ratio of 0.80, the worst in the league, behind Edmonton (0.81), Toronto (0.81), Arizona (0.88), Calgary (0.88), and Buffalo (0.89).
In short, the Ottawa Senators are a lottery team with any other defenseman other than Erik Karlsson in that spot. That example is with a guy who creates 70% as much offense, so like a Kris Letang, for example....if you replaced Karlsson with like an average UFA signing like James Wisniewski for example, the Sens are likely a historically bad team this year.
People like to mention doughty for Norris, but if you swapped Doughty for Letang the kings would still be one of the leagues best teams. The Sens would be running away with the best lotto odds.