Did the Cardinals overpay on Matt Carpenter's extension?

With the recent news that the Cardinals are close to signing Matt Carpenter to an extension, estimated to be for 6 years and around $50 to $55 million, it got me to thinking what is Carpenter really worth and are the Cards overpaying?

Per Fangraphs "Value" calculation, Matt Carpenter's 2013 season would have been worth $35.1 million, based on what a player would make in free agency.

However, Carpenter was not even eligible for arbitration and the Cardinals would have had him under team control through the 2017 season.  With the extension, the Cards will buy out his arbitration years plus two years of free agency, locking him up through the 2019 season.

Thus, even though his season was worth $35 million in free agency (for which he was only paid around $500K), the fact that he is under team control gives the Cardinals significant leverage and allows them to pay a lot less than that to keep him around.

So, instead of looking at his value on the free market, let's compare his value to other players who have signed extensions recently.

To do this, I first looked at all players who have signed extensions since the end of last season, utilizing mlbtraderumors.com's Extension Tracker.   There were 20 such players.  I then narrowed the list down to those players who were pre-arbitration when they signed their extensions, like Carpenter, which left me with 10 players.  I then calculated the average annual salary of their deals and the average WAR per year (prior to signing the extension) to determine the average dollars per WAR.

Here is what I came up with:


Based on the above, the average dollars per WAR was $2.66 million.  Carpenter's contract pays him $52 million over 6 years or $8.67 million per year.  In his 2.012 seasons, he has accumulated 7.50 WAR, giving him a 3.73 average.  Thus, his contracts pays him $2.32 million per WAR.

Thus, from the above, we can conclude that the value of Carpenter's contract is reasonable and, given his performance last season, the Cardinals probably got a bargain, if Carp can keep it up.