Here's a comparison between the two (Coffey's accomplishments at Karlssons current age)
Bolded are players they finished ahead of in norris, hart, point finishes etc
Erik Karlsson
Norris finishes: 1, 1, 2, 2, 7, 18
Norris competition
2011-12: Weber, Chara, Pietrangelo, Lidstrom, Girardi
2014-15: Doughty, Subban, Weber, Josi, Giordano
2015-16: Doughty, Burns, Letang, Josi, Klingberg
2016-17: Burns, Hedman, Keith, Suter, Weber
Hart finishes: 5, 8, 9, 9
Hart competition
2016-17: McDavid, Crosby, Bobrovsky, Burns, Kane
Points
2011-12 NHL 78 (10th)
2015-16 NHL 82 (4th) Kane, Benn, Crosby, Thornton, Wheeler
PPG
2015-16 NHL 1.00 (6th)
Assists
2011-12 NHL 59 (3rd)
2013-14 NHL 54 (7th)
2015-16 NHL 66 (1st)
2016-17 NHL 54 (6th)
APG
2011-12 NHL 0.73 (4th)
2015-16 NHL 0.80 (1st)
2016-17 NHL 0.70 (5th)
Paul Coffey
Norris finishes: 1, 1, 2, 3, 5, 5, 7
Norris competition
1981-82: Wilson, Bourque, Hartsburg, Robinson, Engblom
1982-83: Langway, Howe, Bourque, Wilson, Huddy
1983-84: Langway, Bourque, Potvin, Housley, Stevens
1984-85: Bourque, Langway, Wilson, Stevens, Howe
1985-86: Howe, Robinson, Bourque, Langway, Babych
1986-87: Bourque, Howe, Murphy, Robinson, MacInnis
Hart finishes: 4, 10, 15
Hart competition: Gretzky, Lemieux, Howe, Vanbiesbrouck, Bossy
Points
1983-84 NHL 126 (2nd) Gretzky, Goulet, Stastny, Bossy, Pederson
1984-85 NHL 121 (5th) Gretzky, Kurri, Hawerchuk, Dionne, Bossy
1985-86 NHL 138 (3rd) Gretzky, Lemieux, Kurri, Bossy, Stastny
PPG
1983-84 NHL 1.57 (6th)
1984-85 NHL 1.51 (6th)
1985-86 NHL 1.75 (3rd)
1987-88 NHL 1.46 (7th)
Assists
1982-83 NHL 67 (4th)
1983-84 NHL 86 (2nd)
1984-85 NHL 84 (2nd)
1985-86 NHL 90 (3rd)
APG
1982-83 NHL 0.84 (4th)
1983-84 NHL 1.07 (2nd)
1984-85 NHL 1.05 (2nd)
1985-86 NHL 1.14 (3rd)
1986-87 NHL 0.85 (4th)
1987-88 NHL 1.13 (3rd)
A few thoughts of my own
Despite being in the same team as Gretzky, Kurri and Messier, Coffey was still able to accumulate hart finishes, his best finish being higher than Karlssons best. One could argue that is negated by the fact that he played in the same line as Gretzky and Kurri thereby increasing his point totals. However, in his later years he may not have reached the same point totals, but his point finishes were still quite impressive ( 6. 6, 9)