I'm really skeptical of that. In fact I'd say Karlsson has negative value. He's a 13th forward making $2 million for another two seasons. It just doesn't make any sense for a team to acquire that contract when they could just sign a superior UFA forward like Hansen, Colborne or Matthias for less money and likely a one-year term.
Of course you are because you've let it be known that your bias against Karlsson clouds your ability to be fair when it comes to assessing his value and abilities. A 13th forward is maybe what he should be on a good team. What he actually is though is a 10th or 11th forward that sees regular time in the top nine and produces about 20 points a season with bad advanced stats. Saying someone like Hansen is superior when he played less than him is shaky at best. Colborne wasn't even an NHL'er last season. Matthias played 27 games last year for the Jets and 45 the year before that. For a guy who in the last two seasons has played about as much as Karlsson did this season, it's hardly a good comparison to make. Karlsson is a proven regular in the lineup of a good team that produces relatively well. Those forwards aren't superior and wouldn't provide what Karlsson does even though I think he plays too much and had an awful season.
I'd put Melker Karlsson's value to be about what Tommy Wingels' value was in a trade. A couple minor leaguers and a 7th round pick.