It was announced this morning that the Detroit Tigers have signed free agent catcher Victor Martinez to a 4 year, $50M deal. At a quick glance, it didn't initially seem like a terrible deal. $50M over 4 years translates to $12.5M per season, which puts the onus on Martinez to be worth between +3 and +3.5 wins each season, depending on what you value +1 WAR to equal. Over the past couple seasons I have used $3.5M per 1 WAR, however I think it makes sense to boost that a little bit. But ignoring that for a second, achieving that WAR per season total has not been a huge issue for Martinez; going by a minimum of 300 plate appearances, Martinez has been able to top that marker 6 out of 6 seasons, using Fangraphs' WAR.
Our issue here though, is Martinez is an aging catcher -- he'll be 32 by next Opening Day -- and one that is not very good defensively as is. I'm going to steal Dave Cameron's rough projections for Martinez, and project him to be worth +3.5, +2.5, +1.5, and +1.0 WAR over the next 4 seasons. Now lets take a look and see how that looks using my old measure, $3.5M per 1 WAR, and a more inflated (and perhaps more realistic) measure of $4M per 1 WAR.
First, the old measure ($3.5M per 1 WAR):
Yeah, that's not pretty. In this scenario, which assumes the price of a win will remain down, the Tigers will be overpaying by just over $20M.
Now, the newer measure ($4M per 1 WAR):
Like the older measure, this still doesn't look very pretty. Instead of overpaying by $20M+, they are now overpaying by $16M. That's still quite bad.
I even went a little further and adjusted the price of a win to $4.5M, and the Tigers would still be overpaying by a large sum: $12M.
Overall, this deal looks quite poor. If you were getting Martinez for his, say, age 27 to 31 years, it would probably be fine, since he'd be a strong bet to consistently outproduce a +3 to +3.5 WAR. But that's not the Victor Martinez that Detroit is getting. They are getting the older version, whose defense at catcher is already weak, and an increase of playing time at DH will surely harm his positional value. I think this is just another case of Detroit overpaying someone that is probably not going to be worth the investment.