A pair of American League teams got together last week to make the first major trade of the offseason, as the Mariners dealt ace James Paxton to the Yankees in exchange for a three-prospect package headlined by left-hander Justus Sheffield, the former New York top prospect who now ranks No. 1 on the Mariners' Top 30.
And with rumors now circulating about the Mets' possible willingness to part with some of their top prospects, it seems increasingly likely that there will be even more young talent dealt as the offseason unfolds -- especially with the Winter Meetings on the horizon and a blockbuster class of free agents yet to sign.
Of course, trades involving highly touted prospects for big leaguers such as the recent Yankees-Mariners deal usually happen between a competitive, win-now team and one that's rebuilding.
So which prospects are realistic candidates to be traded this offseason? Here is a look at one player from each organization.
Anthony Alford, OF, Blue Jays No. 5
The former two-sport star opened last season on the disabled list with a hamstring strain, then struggled once healthy, hitting .238 in the Minors (112 games) and .105 over parts of 13 games with Toronto. Alford, 24, still has loud tools, as well as untapped potential at the plate that, if it all clicks, could make him an everyday outfielder capable of contributing in all facets of the game.
Luis Gonzalez, LHP, Orioles No. 29
The fact that the Orioles opted not to add Gonzalez to their 40-man roster last week makes him one of the more interesting relievers available in next month's Rule 5 Draft. Should he go unselected, Gonzalez could be a trade target for teams that value the 26-year-old left-hander's ability to get outs against both left- (.229/.288/.393 in 2018) and right-handed (.206/.288/.285) hitters.
Nick Solak, 2B/OF, Rays No. 11
Solak flirted with a 20-20 campaign in 2018 before finishing with 19 homers, 21 steals and a .282/.384/.450 line over 126 games at Double-A Montgomery. That combination of hitting ability, power and speed, along with his ability to bounce between second base and left field, is why the Rays acquired him from the Yankees last offseason as part of a three-team trade with the D-backs. But with so much talent in Tampa Bay's system, including numerous players with similar profiles ahead of him on the depth chart, Solak could be expendable in the right deal.
Darwinzon Hernandez, LHP, Red Sox No. 7
The Red Sox have a glut of power-hitting third-base prospects, led by Michael Chavis and Bobby Dalbec, but Hernandez might be more attractive to other clubs. He dominated as a reliever in the Arizona Fall League with an upper-90s fastball and a curveball with outstanding spin rates.
Estevan Florial, OF, Yankees No. 1 (MLB No. 45)
The Yankees already proved they're willing to trade their No. 1 prospect when they shipped Sheffield to the Mariners in the Paxton deal. So why wouldn't they part with their new No. 1 -- Florial, who may have a higher ceiling but isn't nearly as ready -- if they could get another instant upgrade?
Video: Florial on improving in the Arizona Fall League
Aaron Civale, RHP, Indians No. 18
Civale's strikeout numbers dipped in his first Double-A campaign, and he also spent a month on the disabled list with right shoulder soreness. But the 2016 third-rounder once again demonstrated plus control (1.8 walks per nine innings) with strong ground-ball tendencies. Provided he's healthy, the 23-year-old right-hander has a realistic chance of contributing as a backend starter or long reliever.
Kelvin Gutierrez, 3B, Royals No. 17
The Royals aren't exactly in a position where they're going to be dealing prospects. They have a pair of similar third basemen in the Minors in Emmanuel Rivera and Gutierrez, so perhaps one could get traded. Gutierrez, who has a line-drive bat with solid defensive skills, arrived from the Nationals as part of a package for Kelvin Herrera in June.
Kyle Funkhouser, RHP, Tigers No. 9
After an injury-riddled first full season, Funkhouser was treated cautiously in 2018 in terms of workload, though he missed a decent amount of bats and mostly induced ground-ball outs in Double-A. With the team in full rebuild mode, it's unlikely prospects will get unloaded, but Funkhouser's unclear long-term role (could he end up a reliever?), but solid stuff, could make him a trade target.
Luis Arraez, 2B, Twins No. 15
Arraez won the Midwest League batting title in 2016, but he missed nearly all of '17 with a torn ACL. He bounced back in 2018, again hitting above .300 and reaching Double-A. He doesn't have a true defensive profile, moving around the infield some this past season, and the Twins have Nick Gordon ahead of him up the middle prospect-wise.
Luis Alexander Basabe, OF, White Sox No. 9
The deepest position in one of baseball's best farm systems is outfielder. Eloy Jimenez is a building block and Luis Robert electrified scouts with his Arizona Fall League performance, so Basabe (a switch-hitting center fielder with five-tool upside) could be a centerpiece in a prospects-for-veteran trade. The White Sox have been linked to more than a few of those types of deals, and they actually acquired Basabe in such a transaction, the Chris Sale trade with the Red Sox at the 2016 Winter Meetings.
Video: Top Prospects: Luis Alexander Basabe, OF, White Sox
Jorge Mateo, SS/OF, A's No. 7
Mateo regressed offensively last season in his first Triple-A campaign, as he hit .230/.280/.353 with a 27.3 percent strikeout rate over 131 games in the Pacific Coast League. The former Top 100 prospect still racked up 25 steals with his top-of-the-scale speed -- giving him 259 stolen bases in 583 career games in the Minors -- and also held his own in return to everyday shortstop duties. Those qualities could make him an intriguing trade chip for the A's this offseason, especially in a deal with a team that believes he has untapped potential at the plate.
Matt Thaiss, 1B, Angels No. 5
Drafted as a catcher in the first round of the 2016 Draft, Thaiss has since moved to first base. He's coming off a solid second full season of pro ball, one that saw him hit 16 homers and spend much of the year in Triple-A. But with Albert Pujols and Shohei Ohtani taking up the first base and DH spots, there's really no room in Los Angeles for Thaiss.
J.B. Bukauskas, RHP, Astros No. 8
If the Nationals had followed through on a trade to send Bryce Harper to the Astros in July, Bukauskas reportedly would have been the top prospect sent to Washington. Houston has a seemingly endless supply of pitching prospects and is more likely to part with him than Forrest Whitley or Josh James.
Video: Bukauskas on his Fall League win over Peoria
Nick Rumbelow, RHP, Mariners No. 19
Seattle traded two pitching prospects for Rumbelow last offseason with the hope that he'd be a key part of their 2018 bullpen. After neck and shoulder injuries sidelined him for the first three months of the season, the 27-year-old righty made 13 appearances across five big league stints with the Mariners, striking out 16 batters in 17 2/3 frames. With the club seemingly entering a rebuild, Rumbelow could intrigue teams in need of a cost-controlled reliever.
Yohander Mendez, LHP, Rangers No. 16
The rebuilding Rangers are looking to add young talent rather than part with it. But maybe a change of scenery would benefit Mendez, who was once one of the game's top lefty pitching prospects but has seen his stock drop during the last two seasons.
Luiz Gohara, LHP, Braves No. 7 (MLB No. 78)
Though Gohara struggled to be consistent in 2018, he's still a lefty with plus stuff who is only 22 years old. The Braves, though, have so much pitching depth and only so many spots as they look to compete in '19. Gohara has top-half-of-the-rotation potential with an intriguing fallback of being a power lefty reliever if all else fails.
McKenzie Mills, LHP, Marlins No. 30
Acquired from the Phillies last August for Justin Bour, Mills received his first taste of the Double-A level following the trade after he had posted a 3.51 ERA with 85 strikeouts over 89 2/3 innings at Class A Advanced Clearwater. While the 6-foot-4 lefty may not have overpowering stuff, he has a good feel for mixing three pitches that all grade as average or better and is consistently around the strike zone.
Gavin Cecchini, 2B/SS, Mets No. 21
The 2012 first-rounder hasn't developed into the regular the Mets hoped he'd become, and he missed three months of the '18 season with a foot injury. He does have a solid history of hitting and has seen time at second or short, but he's not an everyday player at shortstop (nor would he be, with Amed Rosario in his way) and second looks like it could potentially be taken by Robinson Cano in 2019.
Daniel Johnson, OF, Nationals No. 7
Johnson totaled 22 homers and 22 steals in 2017 during a breakout first full season, but a broken hamate bone in his hand curbed much of that power last season in Double-A. The 23-year-old outfielder still put together a solid campaign, hitting .267/.321/.410 with six homers and 21 steals, and then continued to flash his set of impressive tools -- four of which grade out as above-average or better -- during his second tour of the Arizona Fall League.
Adonis Medina, RHP, Phillies No. 3 (MLB No. 64)
The Phillies took a nice step forward in 2018 and could be ready to compete next season, so they might be willing to part with good prospects to improve the big league roster. Medina has terrific stuff and will be reaching the upper levels, positives for inquiring teams, but he's not knocking on the door yet and is less likely to help in Philadelphia in '19.
Video: Top Prospects: Adonis Medina, RHP, Phillies
Corey Ray, OF, Brewers No. 2
The Brewers sold high on several outfield prospects last offseason when they dealt Lewis Brinson and Monte Harrison to the Marlins in the Christian Yelich blockbuster, which in turn set up their signing of free agent Lorenzo Cain, and it's conceivable that Milwaukee could again trade from its Minor League outfield depth as it addresses needs ahead of 2019. Ray, with his blend of power and speed, could help them command another considerable return after he finished his first Double-A season with 27 homers, 66 extra-base hits and 37 steals.
Andrew Knizner, C, Cardinals No. 5
It's always good to have catching depth at the upper levels, especially considering the injury risk. And yes, Yadier Molina isn't getting any younger. But Molina has two years left on his contract and Carson Kelly backing him up/waiting in the wings. Knizner continues to hit (.313/.368/.430 in 2018) and is ready for a big league opportunity.
Brailyn Marquez, LHP, Cubs No. 4
The Cubs are in win-now mode, making it more probable that they'd part with a promising lefty who has made only two appearances in full-season ball. Marquez might have a higher ceiling than any pitcher in Chicago's system, reaching 98 mph with his fastball and flashing a plus curveball as a 19-year-old.
Luis Escobar, RHP, Pirates No. 11
The Pirates strayed from their typical operating procedure when they dealt top-level prospects to Tampa Bay in the Chris Archer deal. It's unlikely they'd do that again with, say, a Mitch Keller type. But Escobar reached Double-A in 2018, proved tough to hit (.225 batting average against) and got ground-ball outs. At worst, a team could be getting a solid reliever whose stuff would play up in shorter stints.
Shed Long, 2B, Reds No. 8
Long can hit and has some pop from the left side, fitting the profile well of an offensive-minded second baseman, one who could be ready at some point in 2019. But the Reds have Scooter Gennett coming off an All-Star season and under contract for another year.
Video: Top Prospects: Shed Long, 2B, Reds
Yoan Lopez, RHP, D-backs No. 18
Off-field issues and injuries slowed the right-hander after he signed for a bonus of more than $8 million in 2015, but he righted the ship as a reliever in '18, went to the Futures Game and made his big league debut. He has the stuff to pitch late in games, something teams with weak bullpens always covet.
Will Smith, C, Dodgers No. 5
With Keibert Ruiz, Smith, Diego Cartaya (MLB Pipeline's top-rated international prospect this summer) and Connor Wong, the Dodgers have more depth in catching prospects than any organization. Los Angeles seems determined to hold onto its top farmhands (Alex Verdugo, Ruiz, Dustin May, Gavin Lux) but could part with the athletic Smith in the right blockbuster deal.
Aramis Garcia, C, Giants No. 15
The Giants don't have much reason to trade youngsters. But Garcia has gone from once being projected as Buster Posey's eventual successor to being supplanted by Joey Bart, the No. 2 overall pick in the 2018 Draft, so he's expendable.
Luis Patino, RHP, Padres No. 9 (MLB No. 83)
As the owners of baseball's best farm system, the Padres are in a position to cash in on their wealth of high-end prospects in a blockbuster-type deal, should they choose that route. Patino showed front-of-the-rotation upside and emerged as a top prospect last season as he posted a 2.16 ERA with 98 strikeouts and a .220 BAA over 83 1/3 innings at age 18 in the Class A Midwest League.
Video: Padres Prospect: Luis Patino
Sam Hilliard, OF, Rockies No. 9
One of several Rockies prospects to shine in the Arizona Fall League, Hilliard has an interesting package of tools, yet also fanned in 31 percent of his plate appearances in Double-A this past season. He's a high-risk, high-reward type who's a year away, and Colorado could cash him in for more immediate help.
Mike Rosenbaum is a reporter for MLB.com. Follow him on Twitter at @GoldenSombrero.
Jim Callis is a reporter for MLB.com. Follow @jimcallisMLB on Twitter. Listen to him on the weekly Pipeline Podcast.
Jonathan Mayo is a reporter for MLB Pipeline. Follow him on Twitter @JonathanMayo and Facebook, and listen to him on the weekly Pipeline Podcast.