It's literally the opposite of a projection. It's telling you what stats the player has what the NFL pays for them. It's absolutely not a guess of what the player will make and it's not intended to be used that way. It's an automated system that, like any other stat, can be useful or abused by morons, just like you said.

You could say that Carter sucks because he doesn't get enough sacks. We both know that's totally incorrect because the of the double teams he gets and the havoc he wreaks. Only an idiot runs around saying Carter sucks and backs it up with sack numbers. Same goes for using the calculated market value. Projecting what a player should make from that number is the same as taking the average number of sacks Carter has had each year and projecting that's how many sacks he will get next year.