All you can really say is they potentially improved the team by taking a risk. Time will tell. He scored 12 goals. A year ago Pitlick had 18, but got injured a lot this year. His first year hear he was pretty good depth scoring. I think you will find nearly every player varies in how many goals they score year to year. A "20 goal scorer" is more likely to have seasons of 15 and 25, etc.
This team needs to add about a goal a game, IMHO. That would put them second in the league, as they were in 2015. Half a goal a game gets them to 12th in the NHL (based on last years stats). Yeah, you might not get all 40 of those from a Panarin, and 12 more is better than none.
IMHO, Nill got younger, a bit cheaper, maybe more coach friendly (Pitlick not a Monty guy maybe?) and probably a bit tougher, again, IMHO, a response to seeing STL win the Cup with a banging style. Adding one 3/4th line bruiser doesn't directly solve this teams problems. For more goal scoring, I fear it will come from the dreaded "internal improvement". Seems like Nill makes big splashes in alternate years (according probably to cap money) With the reduced cap, I can see him going for less expensive UFA (Nyquist maybe) rather than the big fish.
And, honestly, not sure getting 35 goals from the breadman for $10M is much better than 20 goals from Nyquist for half that, and filling in the other 20 goals needed with the Harman's of the world, which I think may be your point.