Could J.T. Realmuto, left, and Bryce Harper find themselves as teammates next season? (John McDonnell/The Washington Post)

A quick study of the Nationals’ offseason history reveals a consistent willingness to fill present and future needs via trade. With an all-but-set starting lineup, a mostly returning rotation and a more solid back of the bullpen than they normally have set up this time of year, the Nationals do not necessarily need to initiate a blockbuster. But after they crossed the luxury tax threshold for the first time in their history in 2017, the Nationals might find the trade market holds as many — if not more — cost-effective and creative options as free agency.

As usual, expect General Manager Mike Rizzo to call on all the biggest names tossed around as available this winter. Are Giancarlo Stanton or Josh Donaldson likely fits? Probably not. But inquiries into players of that caliber should not constitute a surprise, nor anything more than due diligence. One of the greatest home run hitters of the generation is potentially available. You should probably make a call, just in case.

But the Nationals’ targets likely fill a slightly lower stardom tier. They do not need a Stanton or a Donaldson. They need a productive catcher, if they don’t believe they have one in Matt Wieters. They need a stronger bullpen and to fill out their bench, as theirs have been perforated by free agency. And they probably need another reliable starting pitcher — perhaps even a middle-of-the-rotation type.

If the Marlins do sell, Stanton might be less appealing to the Nationals than their catcher, J.T. Realmuto, who is 26 and under team control through 2021. Realmuto hit .278 with 17 homers in 2017, and finished third among major league catchers in FanGraphs WAR with 3.6. Only Gary Sanchez and Buster Posey ranked higher.

If not Realmuto, the Nationals could find plenty of veteran catching help on the free agent market. Perhaps Pittsburgh would make Francisco Cervelli available, given the size of his contract and the always limited size of their payroll. But Realmuto, if he is available, seems like the most intriguing option.

One component of the Nationals’ bench has assumed greater importance in the last month or so, and that is the position of backup infielder. With Daniel Murphy’s status uncertain due to knee surgery that could keep him out past Opening Day, the Nationals must decide whether Wilmer Difo can handle everyday duties reliably — and who else might be able to serve as a fill-in. Several middle infield types could be available via trade this winter, as Ian Kinsler, Brian Dozier and Cesar Hernandez all could be pried away from their teams. But those are more everyday type players, and the Nationals do not need to pay that price with Murphy returning and Difo seemingly ready to assume everyday duties if Murphy departs to free agency next winter.

Perhaps a deal such as the one they made for Yunel Escobar two seasons ago — a relatively low-profile deal that yielded a proven regular — could provide that depth. Jed Lowrie could be available, among others. Perhaps free agency makes the most sense to find a low-cost option, perhaps even familiar free agent Howie Kendrick. Maybe the Nationals make a play for a potential future regular, such as forlorn Rangers prospect Jurickson Profar, in whom they have expressed interest before.

Bullpen options abound this time of year, and at the trade deadline, but a few names jump out as ones the Nationals could pursue. Reds closer Rasiel Iglesias could command a significant return, but is one of the budding young back-end stars available, and not yet at peak Andrew-Miller-or-Aroldis-Chapman-at-the-deadline value. Royals right-hander Kelvin Herrera, 27, intrigued the Nationals at the trade deadline and could do so again this winter. The same is true of Padres left-hander Brad Hand, on whom they would be betting high after a career year. Tigers right-hander Shane Greene could interest them. While the Orioles could once again make Zach Britton available, the Nationals seem an unlikely fit given all the jostling between the geographic rivals.

As for starting pitching, the trade market has yet to develop to the point of clarity, but some interesting names include Twins starter Earvin Santana, Rays starter Jake Odorizzi and maybe even Pirates right-hander Gerrit Cole, a 27-year-old Scott Boras client who has two years of team control remaining. If the Tigers somehow decide to make young phenom Michael Fulmer available, the Nationals would likely be among 25 or more interested callers. These are just a few of the names who could catch their eye — if, of course, the Nationals decide that A.J. Cole and Erick Fedde are not reliable enough options to fill out their rotation.

Rizzo has never displayed much comfort with his pitching depth, always erring toward the side of adding — until he traded away Lucas Giolito and Reynaldo Lopez for Adam Eaton last winter. The Nationals’ minor leagues are thin on big league-ready pitching since that deal, so Rizzo seems far more likely to deal for it than from it.

And therein lies the most pressing question for the Nationals as they peruse the trade market this winter: What exactly do they have to give?

The answer is young and athletic outfielders. While the Nationals did not entertain trade proposals that included prospects Victor Robles or Juan Soto at the deadline and seem unlikely to pivot now, they have Adam Eaton and Bryce Harper penciled in to two outfield spots next season with sudden Gold Glove finalist Michael A. Taylor to play center field between them. That plan leaves no place for Robles, who has looked ready for the majors at every turn and made the playoff roster as a result. He is unproven, and could perhaps start next season in Syracuse. But he is coming, and coming quickly.

With Robles on the way, could the Nationals afford to deal Taylor at peak value after his explosive postseason? Or would they rather hold their cards and secure an outfield of Eaton, Taylor and Robles for years to come, even if Harper leaves in free agency next winter? If they do hold Taylor, what might Brian Goodwin, Rafael Bautista, Andrew Stevenson or even meteoric riser and organizational player of the year Daniel Johnson bring them? Enough to make a big deal? Enough to make a smaller one?

The answers will come in time because the Nationals will undoubtedly ask those questions of several teams this offseason, in some form or another. For now, the trade market does seem to hold plenty of intriguing possibilities for Rizzo and Co. The question is whether they have enough intriguing possibilities to send elsewhere in return.

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