Don't worry, you're not the only one. I'm not totally convinced the guys awarding the compensatory picks understand the secret formula.
The contract size appears to be the overriding consideration.
Also, comparing comp picks from one year to the next is somewhat an apples-to-oranges situation. Since a maximum of 32 comp picks are awarded each year, the composition of the free agent signings across the league influences the award for a particular guy. For example, the more medium-to-big contracts signed in a particular year, the lower the comp pick (or no pick) for lesser-paid players.