FYI, SM-liiga's regular season is now finished and playoffs are about to start. Karlsson's FEL team, Jokerit, won the regular season and Karlsson was also the best defenseman in points in the whole league with 9+25=34 points even though he played only 30 games out of 60.
In the FEL, the winning team receives 3 points from a regulation win, 2 points from an OT or S/O win and 1 point if the team loses in OT or S/O. I've converted the results below to NHL points.
Without Karlsson, Jokerit were 17-10-3 = 37 points (12 wins in regulation, 8 ties, 10 losses and 5 wins in OT or S/O = 49 points).
With Karlsson, Jokerit were 21-5-4 = 46 points (16 wins in regulation, 9 ties, 5 losses and 5 wins in OT or S/O = 62 points).
The stats don't lie. Jokerit were a better team with Karlsson onboard.
Ottawa has been 7-5-2 = 16 pts with Karlsson in 14 games and 6-3-3 = 15 pts without Karlsson in 12 games, so Erik's impact with Ottawa is not as big as with Jokerit.