Salary is a reasonable criterium when talking about players but be careful because a PF with reasonable outside skills and good inside skills will be better than a PF with bad outside skills and excellent inside skills in a lot of games. Yet the latter will have a higher salary. Another thing is the experience which doesnt influence salary.
So, in my opinion, the only position where salary says a lot about quality are pure centers. Yet the skillset says most. Salary is just a rough approximation of the level of a player but the real quality depends on the skillset and thus the quality of the manager who trained this player.