Abdelkader also played three minutes more per game too and spent practically all of that time with Z and/or Datsyuk.
Z isn't as good anymore so playing with him isn't as awesome as it used to be. Nyquist plays with Tatar who has some of the best possession numbers on the team (better than Zetterberg's) .. Not to mention Nyquist plays against lesser competition more often than not as well.
Additionally Abdelkader's ice time also goes towards penalty killing. About 1.5 minutes per game he plays shorthanded. Something Nyquist doesn't do.
Even with less ice time, Nyquist managed to take more shots on goal over the course of the year. Yet Abdelkader had 4 game winning goals to Nyquist's 3.
No matter how one cuts it. Abdekader makes less money, has about the same points as Nyquist and does more on ice with penalty killing, blocked shots, hits (team leader for hits btw) and fighting.
I'd say for all the things I listed, in terms of money the Red Wings management is getting a bigger bang for their buck with Abdelkader's deal compared to Nyquist's deal at the moment.