Aaron Hill Extension: An Analysis

Let's start off by updating the chart we posted after the Upton trade and Prado extension, to reflect the fact that Aaron Hill is no under Diamondback control through 2016. We still don't currently have a yearly breakdown for the extension, so I'll update that, and the totals, when we get that information. Salary info, per Jack Magruder.

As someone mentioned in the signing thread, this means that Kevin Towers could take the next four years off, and the Diamondbacks line-up would more or less take care of itself. There are a couple of less-certain aspects, such as the arrival of Matt Davidson at third. We also need one of the spaghetti Western prospects to become a major-league player (so called, because Kevin Towers is apparently working on his trilogy, A Fistful of Shortstops, For a Few Shortstops More, and The Good, The Bad and Aaron Harang). But, really: three-quarters of the 2016 starting line-up could be the same as what we'll see on Opening Day? That's remarkable stability.

There aren't many directly comparable contracts this off-season. Among second-basemen, the only signing which has been for more than $4 million per year is Marco Scutaro (three years, $20m). Robinson Cano is the big name left, and will likely get a contract to match, despite his record-setting 0-for-29 slump in the postseason last year. Here, with some help from Cot's, is where Hill's new deal puts him among second-basemen with current (or in Cano's case, just expired) contracts. It excludes his pre-existing deal, which pays him $5.5 million this season, but you could throw that in, and the resulting four year, $40.5 million contract would rank Hill in the same spot.

1. Ian Kinsler, $15m (2013-17)
2. Robinson Cano, $14m (2012)
3. Dan Uggla, $12.4m (2011-15)
4. Chase Utley, $12.1m (2007-13)
5. Brandon Phillips, $12.1m (2012-17)
6. Aaron Hill, $11.7m (2014-16)
7. Brian Roberts, $10m (2010-13)
8. Rickie Weeks, $9.7m (2011-14)
9. Dustin Pedroia, $6.8m (2009-14)
10. Marco Scutaro, $6.7m (2013-15)

Last year, Hill trailed only Cano in terms of fWAR among second-basemen, so on that basis, it would seem to be a decent deal. We'd be looking for nine or more wins in the next four years for Hill to be a worthwhile investment, and he put up 6.2 in 2012 alone. However, if extend the sample size to the length of team control - four years, covering 2009-12 - things look rather different. Hill's fWAR isn't even ranked in the top ten, although at a total of 12.3 fWAR, would still represent a solid return on investment, if he matches that going forward. The key word is "if": the contract runs through his age 34 season, so how plausible is that?

I have to switch metrics here, because bWAR allows crunching by age far easier than Fangraphs. With that caveat, how often do second-basemen put up 10+ WAR over their age 31-34 campaigns? Here are those who have done it over the past 25 years.

So, it does happen: it's not common, admittedly, but neither is it out of the bounds of possibility. The last column, pWAR is the amount of bWAR the player in question posted over the previous four years, when he was aged 27-30. As you can see, there is a wide variation, from Bret Boone, who was truly a late bloomer, to the awesomeness which was Chase Utley [who has made this list without even having had an age 34 season yet!]. Oddly, nine of the 12 above put up better numbers after the age of 30 than before it. But the majority were in the 12-14 WAR range going in: while Hill is a little lower, at 10.2, it's certainly not implausible.

If I'd to speculate, this feels like a slight overpay, but not an exorbitant or unrealistic one. My main concern would likely be blocking the likes of Chris Owings from getting a roster spot, but if that comes to pass, it wouldn't exactly be the worst problem in Diamondbacks' history!