"Compensatory draft pick determinations are based on the salary, playing time and postseason honors of the free agents each team lost during the previous offseason...Each team is allowed a maximum of four compensatory picks, and selections will only be awarded to organizations that signed fewer players than they lost to free agency...The exact formula for where each selection will take place may not be known, but the size of the contract each free agent signed has been a major determining factor in previous years."That's the primary factor comp picks- playing time.
I don't think that playing time is exactly the determining factor. It sounds like the size of the contract they sign seems to be the primary category in determining where the team receives their comp pick.