What kind of player will Yoenis Cespedes be going forward?

As I write this, it's looking increasingly likely that the Nationals will swing in and sign Yoenis Cespedes as a free agent. Reports are circulating that the Nationals have offered a five-year deal, and though that doesn't mean anything's finished, the rest of the market hasn't developed like this. The Mets, according to other reports, are holding at three years, and if that were to keep up, Cespedes wouldn't have much of a choice on his hands. Players love security, and Cespedes wants the biggest offer he can land.

An interesting side note is that, from appearances, the Nationals' pursuit of Cespedes is ownership-driven. The owners have made such big moves before, and if Washington's front office thought it was going to grab a high-profile outfielder, it probably wouldn't have recently traded for Ben Revere. Adding Cespedes and Revere would leave someone out of a regular job, and that wouldn't be an ideal circumstance. But it matters only so much how a move happens -- what's more important is what happens next. And the Nationals could soon have to deal with the Cespedes mystery.

First things first, because there are a few layers to this: There's the matter of where Cespedes would play. And the easy answer, and the likely answer, is center field. In theory, Bryce Harper could play center field, but he's pretty well established in right. And though Revere is a center fielder, he'd probably turn into the fourth outfielder, behind Harper, Cespedes and Jayson Werth. So Cespedes would line up in the middle, except for whenever Werth or Harper is out of the lineup, in which case you'd probably see Revere in the middle and Cespedes in a corner. I'm not the manager, but this seems pretty easy.

Cespedes in center field isn't ideal. Granted, Jason Heyward in center field isn't ideal, and the Cubs are lined up to try that. But Heyward is considered an elite defender, and he's younger than Cespedes. There's currently no questioning Cespedes' athleticism, but there's plenty of questioning of his instincts. Statistically, center field has been a problem for him, over smaller samples.

Bringing in Cespedes would also mean a change for Michael Taylor. And that change could be a trade, in exchange for something more immediately useful. The Nationals have at points been linked to some catchers, so maybe this would spur a more aggressive Jonathan Lucroy pursuit. But that's speculation, and I don't know how much the Brewers would like Taylor, if really that much at all.

There's a bigger part of the mystery. Just about any team could happily find a place for Cespedes in 2016. If you've been following all the rumors and reports, you've definitely read several times about how a number of teams are interested in Cespedes on a short-term commitment. Yet Cespedes is also only 30 years old, and Ben Zobrist got four years even though he turns 35 in May. The market has, to this point, expressed a distrust regarding how Cespedes is going to age. This gets at an interesting duality: Cespedes is simultaneously a physical freak, and a guy with a number of red flags.

There have been comparisons between Cespedes and Bo Jackson. I don't need to tell you about Cespedes' physical tools -- so many of them are there, and he runs faster than one might expect. He's always been thought of as being in fantastic shape, and he's remained in fantastic shape. But no matter who signs him -- the Nationals, or someone else -- they won't be signing Cespedes for his late 20s. They'll be getting the start of the 30s, and with this in mind, here's an excerpt from an article by John Harper:

Not that Cespedes is a bad guy, according to sources, so much as someone "who marches to his own drumbeat'" and apparently irritated the Mets at times by not taking batting practice, not hustling during games at times and constantly smoking cigarettes between innings.

I'm not all that interested in a guy's personality. I'm more interested in a guy's commitment, and it's not a good look for Cespedes to be a smoker. It's not a good look to take some plays off, and several articles lately have dropped hints that teams don't know how motivated Cespedes will remain if he signs a big deal. There's very clearly market concern that Cespedes could go south in a hurry. I honestly don't know if that's fair to him, because I don't know him, but the smoking thing is concerning enough on its own. How well is Cespedes going to keep himself conditioned? He wouldn't be the first elite athlete to run out of raw ability. Hanley Ramirez started as a shortstop, but he hasn't consistently put in enough work, and now he's a 32-year-old maybe-first baseman.

There's one neat thing about Cespedes' statistical profile. Let's say, just hypothetically, his conditioning gets worse. He'll probably still be able to hit home runs. And though he'd lose some range in the field -- like all aging players -- Cespedes has actually gotten a ton of value out of his arm. According to Ultimate Zone Rating (UZR), Cespedes for his career as an outfielder has been 21 runs better than average. His arm alone has been 26 runs better than average, meaning the rest of the package has been worth -5. Cespedes' arm has been one of the very best -- better than Alex Gordon's, and worse than only Leonys Martin's. How does arm value age? Does it keep up, even as the rest of the body somewhat deteriorates?

I asked FanGraphs' Jeff Zimmerman to construct an arm-value aging curve. The following is what he produced.

Arm value goes down, at least generally speaking. There's an early peak, and then a gradual decline, which is more or less what we observe with almost everything. The decline isn't huge -- the plot doesn't even cover a difference of five runs. But the range of arm values is already small. Players typically show their best performances earlier in their careers.

Jeff Francoeur, by the numbers, had an absolutely outstanding arm in his 20s. So far in his 30s, he's been basically average. The same pattern happened with Jose Cruz Jr. Vladimir Guerrero was known for his cannon, but he was a little below-average, arm-wise, in his early 30s. That was also true of Jose Guillen. Also true of Alex Rios. On the other hand, Alex Gordon has stayed above average so far. And Ichiro Suzuki had three consecutive excellent arm ratings between 32-34. It seems wise to expect at least a little decline. And quite possibly a significant decline. Especially if you think that Cespedes will have a decline in mobility, since some amount of arm value is actually just getting to the right spots quickly enough to make a difference with a throw.

To this point, Yoenis Cespedes isn't yet a National. Maybe he'll never become one, or maybe he'll become one very shortly. If the reports that are out there are true, the Nationals at least have a leg up, and time is running out. Ultimately, Cespedes is going to sign somewhere for a number of years, and whether that's in Washington or elsewhere, much of the mystery is going to be the same. With another team, Cespedes might fit more easily on the roster. But there's still the uncertainty about how his career is going to play out, more than there usually is. Cespedes has been blessed with a number of physical gifts. Now that he's 30, he'll have to work harder to preserve them. The market, I'd say, has expressed its own belief.