I’m an unabashed fan of Denard Span, and for my money, he remains one of the game’s most underrated players. But I’ll admit that when I saw this a few hours ago, even I was surprised.

Below, a side by side comparison of Span and Jacoby Ellsbury since the start of the 2012 season.

Name PA BB% K% ISO BABIP AVG OBP SLG wOBA wRC+ BsR Off Def WAR Denard Span 1872 7% 11% 0.109 0.318 0.287 0.340 0.396 0.325 105 10.9 21.7 21.4 10.8 Jacoby Ellsbury 1587 7% 14% 0.128 0.316 0.282 0.336 0.410 0.327 104 22.4 28.9 18.6 10.7

Over the last three seasons, Span has essentially been Ellsbury’s equal. They walk the same amount, and while Ellsbury has a tick more power, Span strikes out a little less. Their slash lines are almost identical, and once you adjust for the offensive environments they’ve played in, Span’s wRC+ is actually a point higher, even with less power. Ellsbury’s a better base stealer, but UZR and DRS like Span’s defense a little more. They aren’t perfect clones, but the differences are small, and the overall value has been very similar.

They’re basically the same age — Span was born in February of ’84, Ellsbury in September of ’83 — and have the same general set of skills. Ellsbury’s additional power allows one to see him as a player with a bit more upside — his 2011 season did happen, after all, when he hit as many home runs that year as Span has in his career — and he’s been a slightly better player over his entire career. If you look at their whole big league resume, Ellsbury is at +27 WAR in 3,800 plate appearances, while Span is at +22 in 4,000 plate appearances. On a per-600 PA basis, that gives Ellsbury roughly a +1 WAR advantage.

But the entirety of that difference comes from one year (which occurred four years ago), when Ellsbury was maybe the best player in the game while Span dealt with symptoms from a concussion. That season happened, and it counts, but we’re now on year three of Span and Ellsbury being basically the same player.

The Nationals have a crowded outfield, and the assumption has been that they may look to trade Span this winter. But he’s going to make $9 million next year, and the market just valued a very similar player as a $22 million per year player on a long-term deal. It might be easy to think that Span is a replaceable part, given the team’s depth, let’s not underestimate Span’s impact on the Nationals, and assume that he’d be so easy to replace. Denard Span is really good.