No two players have the same exact set of skills, and certain attributes can't always be measured with statistics. Thus, it's very difficult to claim that "player A" is a perfect comparison for "player B" in any case.
Yet, as baseball fans, player comparisons can be very helpful in understanding what a particular player brings to the table or what that player might bring to the table in the future.
In free agency, player comps take on a whole new level of importance as player agents will argue that their client deserves a certain amount of money because of what a very similar player is making. And teams hoping to keep the price down will try to do the same.
For the eight elite players currently available on the free-agent market—this is based off of my rankings at MLBDepthCharts.com—I've matched them up with a similar player who will serve as a good comparison for what kind of contract they're likely to receive this offseason.
Use the comments section to let me know if you can come up with a better comparison.