I'm not sure why anyone would think Roenick was better than Nicholls offensively:
Scoring finishes in prime years:
Roenick
11, 7, 15, 6, 76 (missed games), 53, 33, 49, 21, 12, 31
Nicholls
15, 13, 16, 20, 38 (missed games), 4, 6, 37, 115 (missed games), 106 (missed games), 137 (missed games), 12, 78 (missed games)
Roenick's finishes here are over an 11-year period, and Nicholls' a 13-year period. If we ignore seasons where each missed a significant number of games, the finishes are:
Roenick
6, 7, 11, 12, 15, 21, 31, 33, 49 [five-best average = 10th; nine-best average = 21st]
Nicholls
4, 6, 12, 13, 15, 16, 20, 37, 38 [five-best average = 10th; nine-best average = 18th]
But, perhaps more notable:
Points peak (and Hockey Ref. adjusted):
Roenick
107, 107, 103, 94, 78 (97, 91, 87, 85, 84 = 88.8 average)
Nicholls
150, 112, 100, 97, 95 (124, 94, 88, 80, 76 = 92.4 average)
And, perhaps most notably:
Chicago Blackhawks' scoring 1995 and 1995-96:
Roenick
101 points in 99 games (1.02 per game)
Nicholls
111 points in 107 games (1.04 per game)
Nicholls was getting old, yet still outscored prime-era Roenick while they were teammates.