Nationals General Manager Mike Rizzo, left, talks with manager Davey Johnson during batting practice at Nationals Park in October. (Alex Brandon/Associated Press)

Here’s what trading a hot minor league prospect for the established, solid Denard Span as your center fielder and leadoff man means to the Washington Nationals.

It’s not just about getting a 28-year-old who’s only a notch below expensive free agent center fielders Michael Bourn, B.J. Upton and Angel Pagan in total value, according to most advanced metrics.

And it’s not just about getting him for the bargain price of $11.25 million for the next two years with a $9 million team option for 2015. That’s the perfect time frame to develop Brian Goodwin and other outfielders.

This is also about opening up options, really nice ones, for the rest of the winter. This is about marking a fairly clear path to a Nats team in 2013 that is at least comparable to last season’s Nats rather than, perhaps, not quite as good.

Now the Nats can go several ways. Two of them are the most obvious. They can, if they choose, offer free agent Adam LaRoche a third year on a deal in hopes of keeping their 100-RBI free agent. If he accepts, they may field one of the best defensive teams of the era with a swift outfield and rangy infield, plus two quality catchers. Their lineup would have excellent balance and five guys with speed. Of course, LaRoche might leave anyway.

Or, if the Nats fear a three-year jam-up at first base (and they seem to dread it), they can let LaRoche drift away, put Michael Morse at first base and keep Tyler Moore and Roger Bernadina as exceptional extra outfielders. That leaves the Nats with a big heap of money to go after a free agent pitcher who will be a significant upgrade on departing Edwin Jackson.

There’s only an infinitesimal chance it’ll be Zack Greinke. The Nats barely consider it, assuming insane L.A. money will keep him an Angel or Dodger.

But look who else is available: Kyle Lohse (16 wins last season with two more in the playoffs), Dan Haren (average 14-11 the last eight years), Anibal Sanchez (Tigers starter in the World Series), Ryan Dempster (13-10 average record, 3.73 ERA the last five years) and others.

The Nats could add Span, keep LaRoche, trade Morse and replace Jackson with an equivalent starter. Or they could add Span, lose LaRoche, move Morse and add a starting pitcher who should be a level better than Jackson and give them a starting rotation that (okay, on paper) is pretty ridiculous.

Now we get to spend the winter waiting to see how, or if, this works out. Either way, or some other way if the opportunistic Mike Rizzo finds one, the Nats’ general manager has positioned himself to improve his team for next season. He hasn’t done it yet. But he has prepared the way.

And in the most likely scenario (LaRoche leaves), adding Span does not damage the Nats’ development plans for their best minor league hitters. Morse will be a free agent next winter. You want first base in 2014? Earn it.

Now, you don’t just count the days until spring training. You count down to the next puzzle piece. For example, the Nats non-tendered John Lannan on Friday and said, “So long.” It was the decent thing to do. Let him start elsewhere. They could have kept Lannan for one last year, even though they would have had to pay him at least $4 million even if he ended up in Class AAA again.

This Span-for-Alex-Meyer trade shows Rizzo’s methods in bright relief.

He does not have an offseason plan. He has multiple plans. Then plans that branch off of those alternate plans. Look at last year. He couldn’t sign his top target, Mark Buehrle, so, three days before Christmas after a pitched battle with reluctant ownership, he made a four-prospects-for-a-star trade for Gio Gonzalez. Then, on Groundhog Day, when it looked like his winter was still a tad sparse, he grabbed Jackson for $11 million.

The team’s stunned manager, Davey Johnson said, “What do we need Jackson for?” But the Nats suddenly had the deepest power rotation in baseball.

The key to grasping where the Nats head next is accepting that Meyer, the 6-foot-9 flamethrower, was probably the team’s best pitching prospect with a ’14 arrival date, either in the rotation or bullpen. All of baseball assumes the Nats will now aim higher in replacing Jackson. But, with lots of salary coming off the books, they can afford it.

The Span trade, however, stands on its own merits. Advanced metrics, such as wins above replacement, say Span (about a 3.5 WAR player over the past five years) is about the same in total value, judged over several seasons, at Upton and Pagan and not much below Bourn.

That’s nice. WAR is a wonderful ideal, like a unified field theory of physics. Call me when they nail either of ’em down. Because Span has no power (nine homers the past three years), I’m not going to rave until I see whether Span ignites the lineup or merely mutes it by taking Bryce Harper out of center field, thus removing a potential 20-homer bat from left field.

Aside from outfield range, Span’s major skill, and a big one, is a better on-base percentage than other options (.342 last season, .357 career) vs. Bourn (.348 and .339), Pagan (.338 and .333) or Upton (.298 and .333). But Upton signed with the Braves for $75 million and the three combined will command more than $200 million.

Now, who hits second? Harper, Jayson Werth, Danny Espinosa? Fill those legal pads.

One mark of Rizzo’s gifts is that while many knew he liked Span and had tried to trade for him, few if any suggested that he’d trade a prospect like Meyer for him. What if Meyer becomes a superstar? Span will never approach that.

That’s probably not the right perspective. This illustrates why the Nats risked offending foes in ’11 when they spent far over “slot” on four high-quality draft picks in the same year; some (such as Anthony Rendon or Brian Goodwin) will play for them while others (like Meyer) turn out to be inventory to trade opportunistically for value-at-a-discount like Span.

You don’t keep getting to make good trades, like grabbing Kurt Suzuki after the trade deadline when he cleared waivers, if you humiliate the other general manager in public every time. You complete trades, like Span for Meyer, because the general manager on the other end of the line thinks, “Rizzo got Gio last winter and he won 21 games. But Billy Beane got what he wanted, too, and they both won their divisions. Why’d the Nats get Suzuki from the A’s? Because Derek Norris was in the Gio trade, too, and he became their starting catcher.”

For now when Rizzo and the Nats call, the thought “win-win” comes to many minds. Once again, Rizzo gave quality to get quality. But the Nats’ general manager also got something else of vague but enormous value the moment be acquired Denard Span: an offseason that’s now filled with better options.

For previous columns by Thomas Boswell, visit