On the face of it, trading a shortstop for a reliever seems like a bad idea. Especially when the shortstop is under team control for a year longer. But teams aren’t vacuums, and you can’t cram all of your players into one depth chart without scraping some elbows. In other words, Yunel Escobar can’t pitch, and Tyler Clippard can. And so maybe this trade between the Athletics and Nationals works for both teams.

It seems from both projections, as well as general approximations of value, that Yunel Escobar can potentially give more value to a team than Tyler Clippard could. Escobar is projected to be just worse than the average major league baseball player by Steamer (1.8 WAR), while Clippard is more likely to be replacement than average (0.3 WAR). One pitches every other day for an inning, the other plays most innings at a premium defensive position.

But that sort of analysis ignores a ton of factors, not the least of which is Clippard’s excellence. Slice your pie anyway you like, and Clippard has been a top-20 reliever since he broke out in 2010. Here are his accolades among his reliever peers.

* Top 15 by WAR since 2010

* Top 10 in RA/9 WAR since 2010

* Top 15 by swinging strike rate since 2009

* Top 25 by strikeout rate since 2010

* Top 30 by strikeout minus walk rate since 2010

* Top 25 by ERA since 2010

* Top 3 by changeup swinging strike rate (21.4%, minimum 300 thrown) in 2014

* Top 3 in changeup pitch type values since 2011

* Number 1 in innings pitched since 2011

* Number 1 in pop-up rate (10.1%, league average is 3.5%) since 2011

That last one is important to your concept of his value. Pop ups are included in WAR, but not included in FIP and not projected by Steamer into his future WAR. But there’s evidence that pop-ups are sticky, year-to-year, and therefore a skill. The year-to-year correlation on pop-ups (.63) is better than the number on home runs allowed (.41). Clippard has consistently put up elite pop-up rates and so that has to be factored into his excellence. (Oakland’s park is also conducive to pop-ups, so he’ll fit in.)

In sum, you have a durable arm that has consistently put up plus strikeout rates and elite pop-up rates on the back of an elite changeup. He’s been worth more than a win a season over the last five seasons (closer to two wins per season if you use RA/9), he was available, and he was cheaper than the other most available pitcher that may have satisfied some of these conditions. Jonathan Papelbon is due at least $13 million compared to Clippard’s $9.3m, and it’s unclear that the rebuilding Phillies would want Yunel Escobar anyway.

Yunel Escobar was due to be paid $5m this year, $7m next year, with a $1m buyout on a $7m option in 2017. If you buy his Steamer projection, you’re buying a bounce back in defense, and if you’re buying a bounce back in defense, Escobar is a good player on a great contract.

Defense is notoriously hard to talk about through the eyes of metrics. But there are a few ways to talk about the skills that go into defense. Speed is important, and Escobar’s speed has been in decline. By speed score, he’s never been above average, but last year’s 1.1 (5.0 is average) was very bad. It was the fourth-worst speed score in baseball last year, and easily the worst by a middle infielder (though J.J. Hardy was close). Since 2011, his speed score is only going down, and at 32, it’s hard to for project him for improvement in that category.

A potentially positive quirk in Escobar’s defensive profile is that he’s very sure-handed. Even including his bad year, Escobar has been top-five in making the Routine plays since 2011 as determined by Inside Edge. He’s been the best shortstop since 2011 at making the Likely plays, too. A shortstop that makes 96.6% of the routine and likely plays is valuable no matter his range.

It’s beyond that where his decreasing range becomes problematic. He’s been 13th in Even plays (plays made 40-60% of the time), and 14th in Unlikely plays. And in last year’s UZR, it was the range portion of his effort that was the most problematic.

To the Athletics, that might have been important, but to the Nationals, his declining defense was less important. Escobar will be asked to play second base for the Nationals. At second, his projected offense (due to be about 4% worse than league average by Steamer) only ranks 23rd by projections, but his defense is likely to be better at the easier position than the other available players on that list — Tommy La Stella, Rickie Weeks, and Yamaico Navarro have much more risk (and poorer defense) associated with them. Escobar is a safe, cost-neutral, major league second baseman.

And the Athletics had a backup plan for Escobar. At the winter meetings, Billy Beane admitted that Marcus Semien (then projected to be an average major league player) was slotted at shortstop. As much as it might have been nice to use Semien as a utility man, how much of an upgrade would he have provided in that role over the likes of Eric Sogard? Judging by our depth charts, Tyler Clippard will push Ryan Cook down out of the setup role and offer as much as a one-win improvement in that spot if you use Clippard’s RA/9 WAR as a guide.

And that’s really the crux of it. Yunel Escobar has averaged about two wins a season for the last five seasons, but fits the Nationals better at a position of need. If you go by Tyler Clippard’s runs allowed — a good idea because he has a rare skill in creating pop-ups — the reliever has averaged 1.8 wins a season for the last five seasons. And he fits the A’s better.

The Athletics traded a shortstop for a reliever and yet it probably made sense for both teams.