Madison Bumgarner is something of an anomaly on the baseball trade market.

It’s not very often a four-time All Star starting pitcher becomes available — especially when said pitcher is a three-time World Series winner with a proven track record of success in the postseason. The San Francisco Giants legend will make $12 million next season before entering free agency at 30 years old. Over the course of his career, Bumgarner has accumulated a 3.03 ERA and is one of the very best southpaws in the sport when healthy.

But pitchers of Bumgarner’s stature have been traded before.

In just the last two years, four starters have been traded after finishing in the top five of their respective league’s Cy Young voting for one of the previous two seasons: Gerrit Cole, Sonny Gray, Chris Sale and Justin Verlander. All four arms were acquired with multiple years of control and had endured varying levels of success.

What really makes Bumgarner unique is the fact that he’s an elite pitcher signed to a team-friendly deal with just one year left of control.

Cole and Gray were coming off disappointing seasons and viewed as reclamation projects. Sale and Verlander, on the other hand, were pitching at outstanding levels, but each had three or more seasons of team control left on their deals — with the latter receiving $28 million a year.

Evaluating Bumgarner’s expected return is no easy task, as there haven’t been any starters of his stature available as a rental in recent memory. But while there aren’t many pitchers traded in recent years worth comparing, one deal completed just last week might be an indicator of what Bumgarner’s market looks like.

Paul Goldschmidt was traded by the Arizona Diamondbacks to the St. Louis Cardinals on Thursday after his fourth-straight season with 155+ games played and an OPS of .899 or higher. He, like Bumgarner, is a free agent after the 2019 season. Yet the package Arizona received only included an MLB-ready catching prospect, two high-floor/low-ceiling players and a compensation pick.

There’s certainly some upside to the players the Diamondbacks acquired. Carson Kelly, the catcher who was the centerpiece of the deal, was given a grade of 55 on the 20-80 prospect scale by MLB Pipeline before he exceeded rookie limits last season. He’ll have the opportunity to start next season in the majors, as will Luke Weaver — a back-end starter who could end up in the bullpen.

But considering Goldschmidt’s talent level, the return is a bit underwhelming. Yes, he’s only guaranteed to play in St. Louis for one season. It still seems like a bargain price to pay in order to acquire one of the best hitters in the game.

The trade market has shifted in recent years, as teams have placed an emphasis on acquiring players signed to cheap, long-term deals. The days of a half season of Aroldis Chapman warranting a package of Gleyber Torres-plus are long gone, weakening the Giants’ position in trade talks. Goldschmidt is also arguably more valuable than Bumgarner; he can make a greater impact by playing every day and boasts a clean bill of health over the past few years.

If the prospects dealt for Goldschmidt are remotely similar to those San Francisco is asking in exchange for Bumgarner, the Washington Nationals should jump all over it. Victor Robles would be completely off the table and it wouldn’t be far-fetched to suggest they could come to an agreement without including the team’s No. 2 prospect Carter Kieboom as well.

The Giants’ farm system is one of the weaker groups in baseball, ranked seventh-worst in the sport by FanGraphs last month. While the Nats didn’t fare much better at 18th overall, they do have MLB Pipeline’s No. 81-ranked prospect in Luis Garcia.

An 18-year-old middle infielder projected to reach the majors in 2021, Garcia (55 grade per MLB Pipeline) is blocked by Kieboom and Trea Turner in the Nats’ organization. His ability to play all over the infield could entice the Giants to build a package around him, especially considering the team isn’t set on sticking with Joe Panik at second base long term.

With Washington still in search of another pitcher to round out the rotation, it could always opt to settle on a lower-floor starter who wouldn’t cost as much as Bumgarner in either prospects or salary. But according to MLB Network’s Jon Morosi, both the Philadelphia Phillies and Atlanta Braves are among the clubs interested in the Giants’ ace.

The NL East arms race only got more heated when Washington outbid the Phillies for Patrick Corbin, putting pressure on the Nats’ division rivals to land a front-line starter. While the Phillies and Braves are playing catch-up from a rotation standpoint, the Nats would cement themselves as the team to beat in the division by acquiring Bumgarner. If anything, their rivals’ interest alone should be enough to convince Washington to at least make an offer.

That’s not to say there won’t be potential snags. Per Cot’s Contracts, the Nats currently sit $18.4 million beneath the $206 million luxury tax threshold — a price tag Washington ownership seems intent on avoiding. Bumgarner’s $12 million would certainly limit the Nats’ ability to shore up its needs of another reliever, second baseman and/or utility infielder.

The team is already reportedly considering trading Tanner Roark (projected to earn $9.8 million in arbitration), which would clear some room for other needs and leave space for potential trade deadline upgrades in July. The No. 5 spot in the rotation would remain a question mark, but it wouldn’t be as much of a concern with Bumgarner, Corbin, Max Scherzer and Stephen Strasburg headlining the starting corps.

Of course, this all hinges on San Francisco’s willingness to deal Bumgarner. The latest reports suggest the Giants and newly hired President of Baseball Operations Farhan Zaidi aren’t close to a deal involving the left-hander, and perhaps that’s because they aren’t seeing offers for packages that interest them. Bumgarner is, after all, a franchise icon and the team is just two years removed from making the playoffs with a similar nucleus.

That being said, Arizona faced a similar dilemma when dealing Goldschmidt. Only Randy Johnson has a higher career WAR in a Diamondbacks uniform. The team made the postseason in 2017 and finished third in the NL West last season, nine games ahead of the Giants. The D-backs eventually made the decision to pull the trigger, and few would be surprised to see San Francisco follow suit.

If Bumgarner is traded by Opening Day, the Nats should be in the thick of negotiations. They’ve been the clear winners of the offseason thus far, but there’s still work to be done if Washington really hopes to make it back to the playoffs in 2019.