Um...a lot?
FanGraphs converts WAR to a dollar value, by way of attempting to estimate what players would be worth on the open market. Naturally, after the exceptional season Joe Mauer had in 2009, that number is positively extortionate.
| Year | Age | WAR | Dollars | MM:WAR |
| 2004 | 21 | 1.3 | $4.0 | $3.08 |
| 2005 | 22 | 3.5 | $12.0 | $3.43 |
| 2006 | 23 | 6.1 | $22.4 | $3.67 |
| 2007 | 24 | 3.0 | $12.3 | $4.10 |
| 2008 | 25 | 5.9 | $26.4 | $4.48 |
| 2009 | 26 | 8.2 | $36.8 | $4.49 |
| Total | 27.9 | $113.9 | $4.08 |
And so, essentially, Mauer's value over the course of his career has been approximately $4,080,000 for every win over replacement. Obviously that nuber has jumped dramatically over the last few years.
Being able to chart an 8.2 WAR is astounding, especially for a catcher. The next closest qualifying catcher compiled a 4.9 WAR in '09, and Victor Martinez fantasy owners were probably pretty happy about that. Is Mauer likely to repeat that kind of success in 2010? I wouldn't put it past him, and nobody in the Twins organization would mind considering that by that point Joe will likely have been extended. But realistically, even for one of the best players in the game that's going to be a tough cookie to bake more than two or three times (even Albert Pujols has topped 8 wins above replacement just three times in his spectacular career).
Let's say, for argument's sake, that Mauer is 7.5 wins average over the next six years. If the millions a player is worth for every win over replacement he is continues to rise, what would a six-year deal for Mauer come out to?
How does $225 million sound? Because that might be a conservative estimate, particularly if A) Joe is worth more than 7.5 wins over replacement across the next six years and/or B) the mean cost per win over replacement is more than $5 million in that span.
My estimates are all monkey estimates/back of a napkin scribblings, so feel free to modify any of this. And of course, FanGraphs value doesn't necessarily translate to real world value.
But the question is: would you sign Joe Mauer to a six-year, $225 million dollar contract? If that seems unreasonable, that's because it is. It's $37.5 million per year, or about as much as Joe was "worth" in 2009 according to FanGraphs.