How much for Joe Mauer?

The Minnesota Twins reportedly are looking to lock up Joe Mauer for eight years at around $165 million. Good deal or bad deal?

Mauer was born in April 1983, which makes him 27 years old for the 2010 season. At the conclusion of his existing contract, he'll be a free agent starting at the age of 28. The best catchers through the age of 27 in the last 50 years are: Johnny Bench, Gary Carter, Carlton Fisk, Ivan Rodriguez and Mike Piazza. How much value did they provide starting at 28?

Wins Above Replacement (WAR) is a framework that was developed at my blog over the past few years. BaseballProjection.com has its implementation of WAR, and it shows the following for these five catchers, starting at age 28 through age 35, for a total of up to 8 seasons:

40: Piazza

34: Rodriguez

32: Carter

30: Fisk

28: Bench

The average for these five catchers is 33 wins, regardless of other positions they may have played during that 8-year time frame. (For those of you wondering, the late bloomer Jorge Posada totaled 32 wins.) To the extent that Mauer is as good as these catchers, then our expectation is for Mauer to generate about 33 wins for his team, over the rest of his career. Of course, Mauer is better than the five on average, and therefore you'd expect more than their average of 33 wins. On the other hand, his best comparison delivered the least out of the five. Let's stick with 33 wins. (Interestingly, the best of these five players through age 27 was Bench, who delivered the fewest wins starting at age 28.)

How much do you pay for those 33 wins over the next eight years? The cost of a win was on an upward slope of about 10 percent annually until two seasons ago. It has reset itself drastically since then. I will use $4 million per win in 2011, and go up by about 7 percent annually over the following years. We should also expect that Mauer will get the bulk of his wins early in his contract. The weighted average cost of these wins will be about $4.9 million per win.

Therefore, Mauer will be worth, on average, about $161 million for the life of his contract. A player being given a long-term contract should come at some discount, say about 10 percent. In that case, Mauer would be worth about $145 million.

Changing the growth rate in baseball salaries will change this forecast. If it reverts back to the 10 percent of recent history, then the weighted cost of a win will be $5.4 million, and therefore, Mauer's average year-to-year value over the next eight years is $176 million. Applying a generic 10 percent discount brings us to $159 million.

So, that's basically the framework you have for a deal, somewhere between $145 million and $176 million to purchase eight years of Mauer's value. The Twins are right on the money.

Tom Tango writes for Inside The Book.