The San Francisco Giants aren't contending this season, so who's interested in trading for an ace starter with four All-Star selections and three World Series rings?

Probably a lot of teams, so it's going to take some effort to whittle down where Madison Bumgarner might go and what he could bring back for the Giants.

According to Ken Rosenthal of The Athletic, the 29-year-old left-hander has an eight-team no-trade list that includes the Atlanta Braves, Boston Red Sox, Chicago Cubs, Houston Astros, Milwaukee Brewers, New York Yankees, Philadelphia Phillies and St. Louis Cardinals.

In all probability, Bumgarner doesn't actually want to avoid those teams. He presumably picked them so he might leverage more money out of a possible deal to one of those franchises.

If we're going to imagine what trades for Bumgarner might look like, there's only one complication: What is his trade value?

What Is Madison Bumgarner's Trade Value?

Barring a possible contract extension with a new team, Bumgarner is ticketed for free agency this winter. So far this season, he has a 4.21 ERA that's over a run higher than his career mark of 3.08.

However, the southpaw is healthy following shoulder and hand injuries in 2017 and 2018, respectively, and it shows in his revitalized fastball velocity and improved strikeout-to-walk ratio. Even if a team just rents him for the remainder of 2019, it'll only take on the remainder of his $12 million salary.

In the best-case scenario, Bumgarner's value would line up with that of Yu Darvish in 2017. He was also a rental ace who wasn't his best self but who was healthy following two injury-marred seasons and generally pitching well. He was also earning just $11 million.

The Texas Rangers traded Darvish to the Los Angeles Dodgers on July 31, 2017 for slugger Willie Calhoun, infielder Brendon Davis and right-hander A.J. Alexy. Calhoun was a top-100 prospect with offensive upside to balance out his defensive red flags. Davis and Alexy ranked in the top 30 of a deep Dodgers farm system.

Let's assume Bumgarner might also fetch three prospects of varying upside. We can't predict exactly what different trade packages would look like. But with an assist from MLB.com's 2019 prospect rankings, we can look at what eight of his suitors have to offer and make educated guesses.

We'll proceed roughly in order of trade likelihood.

San Diego Padres

Even though the San Diego Padres aren't on Bumgarner's no-trade list, they likely won't be in the mix to rent him if they continue to struggle after a warm start to 2019.

Still, perhaps the Padres will rebound and come to see adding Bumgarner to a young rotation as the best way to get over the top. If so, they'll have more than enough prospects to barter with.

The best of them would likely be off-limits, but Logan Allen could be a proper centerpiece. The 21-year-old southpaw is MLB's No. 68 prospect but just the Padres' No. 6. He only has a 4.54 ERA at Triple-A, yet the Giants could latch on to his MLB readiness and outstanding changeup.

The Giants could also angle for the Padres' No. 14 prospect, outfielder Buddy Reed. He's looking up at a crowded outfield in San Diego, so the Padres may be willing to part with his power and speed.

Since that's a pretty good pair of prospects, the third piece might have to be a high-risk, high-reward type. That's Anderson Espinoza in a nutshell. The 21-year-old was once one of the best pitching prospects in baseball. Now he's recovering from his second Tommy John surgery in two years.

The Package: LHP Logan Allen, OF Buddy Reed and RHP Anderson Espinoza

New York Yankees

The New York Yankees are atop the American League East despite some severe bites from the injury bug. So rather than pursue blockbuster trades, they may be content with waiting to get healthy.

Or, they could see a deal for Bumgarner as a means to clad their starting rotation in iron for the remainder of the regular season and the postseason. Perhaps to a point where they would be comfortable with further emptying their diminished farm system.

The Giants would probably insist on toolsy center fielder Estevan Florial, assuming he recovers from a broken right wrist. He's the No. 52 prospect in MLB and the Yankees' No. 1. But since Florial is blocked by Aaron Hicks and there are questions about his hit tool, the Yankees might be willing to part with him.

The other players going to San Francisco would have to be lesser prospects, however. To compromise, the Giants could take on a reclamation project and a long-term upside play.

Right-hander Chance Adams, who's been humbled by Triple-A, would fit the first bill. Fellow righty Tanner Myatt, who must gain control over his electric stuff, would fit the second. They're the Yankees' No. 20 and No. 29 prospects, respectively.

The Package: OF Estevan Florial and RHPs Chance Adams and Tanner Myatt

Philadelphia Phillies

The Philadelphia Phillies are another first-place team that might bypass a trade for Bumgarner, yet dealing for him would certainly help them outpace the Atlanta Braves in the National League East.

The Phillies don't have much left in their farm system, and Maikel Franco's ongoing inconsistency at third base probably makes them loath to part with top prospect Alec Bohm. But the Giants might prefer their No. 2 prospect anyway.

That's right-hander Adonis Medina. He's gotten knocked around at High-A and Double-A, but he's nonetheless a 22-year-old with a strong three-pitch mix, and he could be MLB-ready as soon as 2020.

The Giants might also aim for the Phillies' No. 7 prospect, left-hander JoJo Romero. The 22-year-old has a 9.64 ERA at Triple-A, but his MLB readiness could appeal to the Giants. So might his pitch-to-contact style, which would play better at Oracle Park than at Citizens Bank Park.

To round things out, how about outfielder Cornelius Randolph? The Phillies drafted him No. 10 overall in 2015, but now he's their No. 25 prospect and probably in need of a change of scenery.

The Package: RHP Adonis Medina, LHP JoJo Romero and OF Cornelius Randolph

St. Louis Cardinals

Much more so than the Yankees and Phillies, the St. Louis Cardinals truly need Bumgarner. Their rotation has a 4.58 ERA as a whole, and none of their primary starters has an ERA under 4.00.

Where the Cardinals are at an apparent disadvantage is that their farm system contains only one top-100 prospect. That's third baseman Nolan Gorman, whom the Cardinals would likely prefer to keep as an heir apparent to Matt Carpenter.

If not Gorman, the Giants must at least get Tyler O'Neill. The 23-year-old isn't far removed from being a top prospect on account of his considerable power. In St. Louis, there's no room for him in a crowded outfield. In San Francisco, he would fit in an outfield that sorely needs a slugger.

Given their situation, the Cardinals probably don't want to part with any MLB-ready pitchers. But they might make an exception for lefty Genesis Cabrera. Although he's their No. 8 prospect and a step below the majors at Triple-A, he's still working on controlling his stuff.

The Cardinals also have some infield depth in their system to trade from. Max Schrock, St. Louis' No. 26 prospect, is a sweet-swinging second baseman who could interest the Giants.

The Package: OF Tyler O'Neill, LHP Genesis Cabrera and 2B Max Schrock

Milwaukee Brewers

Elsewhere in the NL Central, there's arguably an even stronger need for Bumgarner in Milwaukee.

Although Brewers starters have been better lately, they still only have a 4.16 ERA. They also don't have an obvious No. 1, and Bumgarner has looked like a good fix for that problem for a while.

According to Jon Paul Morosi of MLB.com, a Bumgarner trade was on the Brewers' minds back in January. At the time, Morosi also reported the Giants would need to get one of Milwaukee's three prized right-handers: Brandon Woodruff, Corbin Burnes or Freddy Peralta.

Woodruff and Burnes have since become important factors in Milwaukee's rotation and bullpen, respectively. Peralta, on the other hand, has wavered with a 6.16 ERA. The Brewers may be OK with risking that the Giants will unlock the 22-year-old's good stuff over the next few years.

The Giants would also need two of the better prospects from a weak Brewers system. Infielder Mauricio Dubon (Milwaukee's No. 5) and outfielder Je'Von Ward (No. 23) stick out as possibilities. Neither is likely to be a star, but the Giants could pin their hopes on Dubon's sweet swing and Ward's tools.

The Package: RHP Freddy Peralta, INF Mauricio Dubon and OF Je'Von Ward

Houston Astros

More so than any other team in Major League Baseball, the Houston Astros are in an ideal position to go all-in for a rental.

They're already on track for a third straight 100-win season. But for the sake of preparing their rotation for October, they could stand to line up a third veteran ace behind Justin Verlander and Gerrit Cole. Besides which, they might as well put their deep farm system to good use.

The trio of right-hander Forrest Whitley and outfielders Kyle Tucker and Yordan Alvarez is probably a no-go zone for prospective trade suitors. But for Bumgarner, the Giants might at least get righty Corbin Martin.

The 23-year-old has recently been using his complete toolset to outperform his No. 58 overall ranking, yet it's debatable whether he has the goods for acehood. The Astros may thus be willing to sacrifice him for their pursuit of a second World Series championship in three years.

The Giants would otherwise have to shop at the lower end of Houston's prospect ranks. MLB-ready righty Rogelio Armenteros (Houston's No. 22) and defensive wiz shortstop Jeremy Pena (No. 25) could be attainable.

The Package: RHPs Corbin Martin and Rogelio Armenteros and SS Jeremy Pena

Minnesota Twins

Like the Padres, the Minnesota Twins have the advantage of not being on Bumgarner's no-trade list. Unlike the Padres, the Twins may indeed have the motive to trade for him.

A deal for Bumgarner would help the Twins keep what's already a strong hold on the AL Central lead. Plus, their rotation could use a veteran of his stature to help carry the load in October.

Minnesota's farm system is headlined by shortstop Royce Lewis and outfielder Alex Kirilloff, both of whom are too good to be shipped away for Bumgarner. But after them is Brusdar Graterol, who's likely more attainable.

The 20-year-old righty comes with a big-time fastball, and he's been using it to put up a 1.89 ERA at Double-A this season. He's therefore arguably better than his No. 61 overall ranking indicates. But since he's not quite MLB-ready, the Twins may be willing to move him for a chance at immediate October glory.

The Giants would have to settle for lesser talents after Graterol. Speedy outfielder Gabriel Maciel (Minnesota's No. 25) and right-hander Luis Rijo (No. 30) have profiles that would suit them well.

The Package: RHPs Brusdar Graterol and Luis Rijo and OF Gabriel Maciel

Atlanta Braves

The Atlanta Braves might not need Bumgarner. Their rotation has been coming together of late, so a trade for an ace reliever is arguably more crucial in their quest for a second straight NL East title.

Yet a veteran lefty like Bumgarner would indeed help an Atlanta rotation that leans right-handed and inexperienced. If the Braves come to the same conclusion, they'd have plenty to offer the Giants.

The Braves wouldn't have to budge on front-line talents like outfielders Cristian Pache and Drew Waters, third baseman Austin Riley and righties Kyle Wright and Ian Anderson. Meanwhile, righty Touki Toussaint is needed in their bullpen.

Fellow righty Bryse Wilson may be fair game, however. The 21-year-old is on the outside looking in at the Braves pitching staff, yet he has a strong three-pitch arsenal to support his No. 80 overall ranking.

The Giants might also go for lefty Luiz Gohara, who looked like a potential star before an all-around terrible 2018. After landing Atlanta's No. 7 and No. 9 prospects, the Giants could set their sights lower at No. 30 with speedy outfielder Justin Dean.

The Package: RHP Bryse Wilson, LHP Luiz Gohara and OF Justin Dean

Stats courtesy of Baseball Reference and FanGraphs.