Last Wednesday, the Nationals solved their center field problem by trading several of their best pitching prospects to the Chicago White Sox in exchange for Adam Eaton. Last Friday, the Cardinals solved their center field problem by giving a bunch of money to free agent Dexter Fowler. Before signing Fowler, the Cardinals tried to trade for Eaton. Had the Nationals not been able to complete a deal for Eaton, they presumably would have been in on Fowler. So, with two teams making different decisions about big investments into how to land a center fielder, let’s compare the two players and the costs it took to acquire them.

Helpfully, Eaton and Fowler are actually pretty similar players. Let’s just start with their offensive skillsets.

Eaton and Fowler, 2014-2016 Name PA BB% K% ISO BABIP AVG OBP SLG wOBA wRC+ BsR Off Adam Eaton 1933 9% 17% 0.132 0.343 0.290 0.362 0.422 0.344 117 12 50 Dexter Fowler 1746 13% 22% 0.153 0.334 0.266 0.369 0.419 0.348 121 10 52

Eaton has slightly better contact skills, so he strikes out a little bit less, but Fowler has a better idea of the strike zone, so he walks a little more. Fowler has a little more power, though not dramatically so. Both are very good baserunners. In the end, they’ve been almost equivalent offensive producers over the last three years.

Defensively, there’s some question marks with both players. Neither one has graded out all that well in center field by either UZR or DRS, but there are reasons to be optimistic about both going forward as defenders at the position.

The Cubs repositioned Fowler last year, and as a result, he was rated as an average defender by both UZR and DRS for the first time in his career. Fowler has always been a guy that scouts thought was better than his defensive metrics suggested, and it’s certainly possible that playing deeper was the simple change he needed to make, which could help him perform better than his track record suggests.

With Eaton, his defensive marks in center aren’t great, but he was rated as one of the game’s elite defenders as a right fielder last year, combining something like league-best range in right field with the most effective throwing arm of any outfielder in the game. And, as Mitchel Lichtman showed over the weekend, the preponderance of the evidence shows that there isn’t really center field defense or right field defense, and the fact that Eaton was staggeringly good in right field means he is very likely to be a better center fielder than his CF-only numbers indicate.

So for both Fowler and Eaton, we have inconsistent defensive data, with the most recent results being much more positive than the older data. Given that you don’t want to draw sweeping conclusions from a single year of defensive data, we still have to include the prior information in our projections of their performance, and not treat them as if 2016 was some kind of new baseline for established performance. With that data included and weighted most heavily, though, both project as slightly below average defenders in center, though with Eaton projecting a few runs better with the glove. Like on offense, though, there isn’t a huge gap here.

So both are good hitters with average-ish gloves in center (though STL and WAS are likely hoping for better than that based on their 2016 numbers), so depending on how much of their offensive performance they retain, that makes them something like +3 WAR players. Steamer is projecting some pretty significant offensive regression for both, with 107/106 wRC+ projections for Fowler and Eaton respectively, while ZIPS was a bit more optimistic about Fowler’s bat, and likely will be with Eaton too, given the differences in aging curves the two systems use.

And, of course, age is a key here, and the place where these two similar players diverge. The Cardinals five year deal for Fowler buys his age 31-35 seasons, while the Nationals traded for the final five years of Eaton’s contract, which gets them his age 28-32 seasons. While it’s instructive to know that Eaton and Fowler are similar players now, our expectation of future production necessarily has to be more optimistic for Eaton, given that he’s three years younger. As a super-basic look at how we might expect age to play into their value, here is what we get from our contract estimating tool, if we start both players as +3 WAR players for 2017.

Adam Eaton’s Contract Estimate — 5 yr / $118.3 M Year Age WAR $/WAR Est. Contract 2017 28 3.0 $8.0 M $24.0 M 2018 29 3.0 $8.4 M $25.2 M 2019 30 3.0 $8.8 M $26.5 M 2020 31 2.5 $9.3 M $23.2 M 2021 32 2.0 $9.7 M $19.4 M Totals 13.5 $118.3 M Assumptions Value: $8M/WAR with 5.0% inflation (for first 5 years)

Aging Curve: +0.25 WAR/yr (18-27), 0 WAR/yr (28-30),-0.5 WAR/yr (31-37),-0.75 WAR/yr (> 37)

Dexter Fowler’s Contract Estimate — 5 yr / $86.3 M Year Age WAR $/WAR Est. Contract 2017 31 3.0 $8.0 M $24.0 M 2018 32 2.5 $8.4 M $21.0 M 2019 33 2.0 $8.8 M $17.6 M 2020 34 1.5 $9.3 M $13.9 M 2021 35 1.0 $9.7 M $9.7 M Totals 10.0 $86.3 M Assumptions Value: $8M/WAR with 5.0% inflation (for first 5 years)

Aging Curve: +0.25 WAR/yr (18-27), 0 WAR/yr (28-30),-0.5 WAR/yr (31-37),-0.75 WAR/yr (> 37)

Note that, at $8 million per win and Fowler as a +3 WAR player, the contract estimator basically nailed the deal Fowler actually signed this winter, so there’s some basis in reality here, even though the assumptions are definitely imprecise. And because of the differences in age, Eaton is expected to put up an additional +3.5 WAR over the life of the deal, earning something like an extra $32 million in value for the Nationals with that additional performance.

Plus, of course, the contracts are quite different. Fowler is going to make $82.5 million over the next five years, while Eaton will make $38.4 million during the same time period, assuming his 2020/2021 options are exercised. The fact that the last two years of Eaton’s deals are option years makes his deal even more team-friendly, as the Nationals exposure is limited if he’s a total bust, but then again, at $10 million per year, the cost is low enough that Eaton would have to crater in an unimaginable way for them to not pick those up. Realistically, we should expect both of those options to be exercised, and can reasonably say that the difference in cost over the next five years is something like $44 million in salary.

So Eaton costs $44 million less in salary and is expected to be worth about $32 million more in performance value; you can see why the Nationals considered him a more preferable option, and were willing to give up significant value to land him from the White Sox. Plus, signing Fowler also cost the Cardinals their 2017 first round draft choice, so we have to account for the tax that goes with signing him as well. Major League teams are valuing end-of-first-round picks at around $10 million apiece these days, so Fowler really cost more like $92.5 million when that is factored in.

With salary, draft pick tax, and aging factored in, these numbers give Eaton something like an $85 million advantage in value. So, to decide whether which team made out better with their center field decision, we have to decide whether we think the prospects the Nationals gave up are worth more than $85 million.

If we just combined the most recent Baseball America rankings — their mid-season Top 100 from July — with the 2016 prospect surplus value calculations, the answer would be an easy yes. Giolito ranked as the #4 prospect in baseball on BA’s summer list, which would make him worth something like $70 million by himself; toss in Lopez as a top-50 pitcher too (another $30 million), plus Dunning having some value as a recent first-round pick, and it’s easy to see why the general consensus seems to be that that the Nationals overpaid here. If Giolito/Lopez are worth more than $100 million in value, then the Nationals should have just signed Fowler instead.

But as we talked about last week, there are a lot of reasons to think that Giolito’s mid-season ranking isn’t a very good indicator of his actual current market value. Giolito has always been a stuff-over-results prospect, but the stuff wasn’t that great in the big leagues, and he wasn’t missing enough bats in the minors to justify that kind of high-end valuation. From KATOH’s stats-only perspective, Giolito ranked as the game’s 74th best prospect in its midseason update, and that was before he bombed in the big leagues.

Talking with a variety of people in the game at the winter meetings last week, it’s pretty clear that Giolito’s stock is down around the game, and there’s a decent amount of skepticism about whether there’s really top-of-the-rotation talent there. Multiple industry folks confirmed that their own internal rankings had him more in the 25-50 range, and that they put a significantly lower value on him than the $70 million valuation that would be expected if he was a legitimate top-10 pitching prospect.

So, realistically, the Fowler/Eaton decision probably comes down to what you think of Giolito at this point. If you see him as a legitimate high-end pitching prospect, still one of the game’s elite prospects, then the Nationals probably gave up more in prospect value than they saved by going with the cheaper and younger Eaton. If you see Giolito as a star in the making, then yeah, they should have just signed Fowler.

But if you see Giolito as more of a standard top 100 pitching prospect, a guy with a good amount of risk to go along with a solid upside, then it’s not so cut-and-dried. If Giolito and Lopez are both middle-of-the-top-100 prospects, both worth about $30 to $40 million, and you give another $10 million or so to Dunning, then the prospect package the Nationals gave up is almost exactly equal to the extra value Eaton would project to have over Fowler.

Except, there’s actually one other area where Eaton provides a fairly substantial advantage for Washington; the luxury tax. The Nationals are actually fairly close to the $195 million CBT threshold, and signing a guy like Fowler would have probably put them over the line, or at least made it close enough that he would have been their only significant free agent signing of the winter. With Eaton’s AAV being less than half of Fowler’s number, he provides space for Washington make a run at another free agent this winter, likely a reliever to help bolster a group that lost Mark Melancon and Marc Rzepczynski to free agency. They probably don’t get Kenley Jansen with that savings, but maybe Eaton’s cheap contract gives them the runway to sign a guy like Greg Holland.

So, at the risk of writing 2,000 words without coming to a conclusion, I’m not sure I see a clear advantage for either option here. Eaton’s cost-savings and age are real advantages, and the extra short-term boost the Nationals could potentially get thanks to his lower CBT number probably make trading for him a better short-term play than signing Fowler would be. Then again, Giolito and Lopez might have been able to fill the bullpen holes the Nationals now have, so perhaps they would not have needed to sign a reliever if they had just signed Fowler instead. And of course, having both of those guys around, you could have continued to bet on their long-term upside, and perhaps come out well ahead if Giolito turned into what he’s been projected as.

But there’s a real chance that Giolito’s value has already peaked, and he’ll be something like Archie Bradley a year from now, a formerly elite pitching prospect who looks more like a back-end starter after struggling against big league hitters. If that’s more of what you expect from Giolito, then cashing him in to save $50 million in salary and get the younger center fielder is probably not a bad idea.

Forced to make a choice, and not knowing what else the Nationals could have gotten for that pair of arms, I think I probably would have just signed Fowler, hoped Lopez turned into the high-end relief arm the Nationals could use, and maybe shopped Giolito for something else, perhaps a better 1B/OF than Ryan Zimmerman or Jayson Werth. But given the costs and expected performances of both Fowler and Eaton, I think it’s fair to say that there are reasons to prefer either option, and the Nationals didn’t clearly screw up by trading for Eaton instead of just throwing more money at Fowler.