How much is too much for Hamilton?

Tim Heitman-USA TODAY Sports

The Mariners are somewhat likely to land Josh Hamilton or Nick Swisher in the next 168 hours. There is little doubt that either player would improve the Mariners’ offense this year, the next year, and probably even the year after that. However, neither player is likely to sign for only three years, so let’s take a look at a longer-term projection.

Using Baseball-Reference’s similarity scores, I gathered both Hamilton and Swisher’s top 10 comparable players (up to and through the age-31 season). I then analyzed the average performance of those ten players in each subsequent season on the downhill side of 31. I looked at the effects of age on these types of players in terms of plate appearances, BABIP, OBP, ISO, Bill James’ Power-Speed statistic, and WAR.

Let’s get started with Josh Hamilton today.

We all know that players tend to get worse with age. For some, that age is 30, and for others, not 30. The best I can do for predicting Josh Hamilton’s aging process is to see how similar players aged. Maybe Hamilton will be different and special, but that’s not a probable outcome.

Hamilton’s ten best comps declined on average each year after they turned 31. The chart below summarized the group’s year –to –year changes.

We can see that the group of Hamilton’s best friends declined in every statistic. Not every player declined every year, but the trend was most definitely downward. And I should point out that these negative changes likely underestimate the effect of aging to some degree since players that chose to retire were not able to be counted. A player that chooses to retire likely does so because he feels that he will do poorly. If we could somehow go back in time and force all the players in our sample to play seven full seasons after the age of 31, we would almost certainly find that the average decline was even more pronounced than that above—especially in terms of WAR. More on this later.

If we assume that Hamilton will be a 5.1-WAR player in 2013, that a win on the open market is currently worth $5M, that the market inflation rate will be 7.5%, and that he will only lose 0.36 WAR each season, then here’s what seven years would look like.

2013

582

5.1

$25.5

2014

542

4.74

$25.5

2015

502

4.38

$25.3

2016

462

4.02

$25.0

2017

422

3.66

$24.4

2018

382

3.3

$23.7

2019

342

2.94

$22.7

3234

28.14

$172.1

Hey, that looks pretty swell! Seven years for $175M—which Hamilton lobbed out there a few weeks ago—doesn’t look so far-fetched with the above assumptions. However, 7.5% inflation is probably a high forecast, and a 0.36-WAR loss per season is quite conservative due to the sampling bias mentioned above. With an inflation rate of 5% and a 0.5-WAR loss per season, this is Hamilton’s outlook:

2013

582

5.1

$25.5

2014

542

4.6

$24.7

2015

502

4.1

$23.7

2016

462

3.6

$22.4

2017

422

3.1

$20.7

2018

382

2.6

$18.7

2019

342

2.1

$16.2

3234

25.2

$151.8

I’m leaning more on the side of the second scenario, though I still think it’s a bit kind to Hamilton. Based on those numbers, I would be pleased if the Mariners signed Hamilton for six years at $125M. Fangraphs crowd sourcing predicted some weeks ago that a Hamilton contract would end up being 5 years for $100M. That would be quite a deal for the signing team, but we just learned that Fangraphs’ readers undershot Zack Greinke by $33M, so I’m not holding my breath on 5/100.

Obviously, none of the comparable players were Josh Hamilton. There were a lot like Josh Hamilton in some statistical ways, but not every way. Hamilton swings at everything, perhaps more like Vladimir Guerrero in that way. Hamilton has a history of drug problems, maybe more like Lenny Dykstra. Hamilton is left-handed and injury prone, maybe more like Ken Griffey, Jr.

For the curious, Dykstra washed up after 31, posting two seasons worth a total 2.6 bWAR. Guerrero had one more good season at 32 with 4.3 bWAR, then disappeared, posting just 4.5 bWAR over his final four seasons. Griffey fought on valiantly, but in the end, he accumulated just 4.3 bWAR in parts of nine seasons after 31.

Is that a study? No. It’s an anecdote. But here’s a fact: just four of Hamilton’s ten comps made it to their age-38 season, the seventh season after 31.

Age is stacked against Hamilton, but I still think he’s worth a six-year contract if the price is in the $125M range. Just don’t Chone Figgins us, please.

Tomorrow, we’ll have some fun with Nick Swisher—at least, with the statistics he has produced. He won’t actually be here with me.