There is always risk involved when it comes to trading prospects.

Some of the most lopsided trades in MLB history have seen teams ship out future Hall of Famers before they made their big league debuts in exchange for established veteran talent, only to watch those young players develop into all-time greats.

John Smoltz and Jeff Bagwell immediately come to mind.

Ahead, we've highlighted the 10 best players in baseball today who were traded before making their MLB debuts and have since developed into stars.

The players were selected based on their expected impact during the 2021 season, which would explain why Adam Wainwright settled for an honorable mention despite accomplishing more from a career resume standpoint than anyone else on the list.

Let's start with some honorable mentions.

Honorable Mentions

Before we dive into our top 10, here are some other notable players who were traded prior to their MLB debuts:

• SS Willy Adames, TB
• SS Nick Ahmed, ARI
• LHP Steven Brault, PIT
• DH Willie Calhoun, TEX
• OF Mark Canha, OAK (Rule 5 pick)
• SS Willi Castro, DET
• RHP Dylan Cease, CWS
• 2B Jake Cronenworth, SD
• RHP Zach Eflin, PHI
• OF Clint Frazier, NYY
• RHP Chad Green, NYY
• RHP Brad Keller, KC (Rule 5 pick)
• RHP Corey Kluber, NYY
• OF Ramon Laureano, OAK
• RHP Pablo Lopez, MIA
• LHP Sean Manaea, OAK
• RHP German Marquez, COL
• OF Tyler O'Neill, STL
• RHP Chris Paddack, SD
• OF Bryan Reynolds, PIT
• 1B Anthony Rizzo, CHC
• LHP Eduardo Rodriguez, BOS
• RHP Sixto Sanchez, MIA
• 2B Nick Solak, TEX
• SS Dansby Swanson, ATL
• RHP Noah Syndergaard, NYM
• RHP Adam Wainwright, STL
• LHP Ryan Yarbrough, TB
• OF Mike Yastrzemski, SF

DH Yordan Alvarez, Houston Astros

Aug. 1, 2016: Los Angeles Dodgers trade 1B/OF Yordan Alvarez to the Houston Astros in exchange for RHP Josh Fields.

At the end of the 2016 international signing period, the Los Angeles Dodgers gave Cuban defector Yordan Alvarez a $2 million signing bonus. Less than two months later, before he ever played a professional game in the Dodgers organization, he was traded to the Houston Astros in exchange for reliever Josh Fields.

To his credit, Fields went on to post a 2.79 ERA and 10.2 strikeouts per nine innings in 22 appearances the rest of the way. All told, he logged a 2.61 ERA with 25 holds over 124 appearances in three seasons with the team.

However, Alvarez quickly emerged as one of baseball's top prospects before bursting onto the scene to win American League Rookie of the Year honors in 2019 when he posted a 173 OPS+ with 27 home runs and 78 RBI in 87 games.

This is not the last time on this list we'll see a contender overpay for bullpen help.

RHP Luis Castillo, Cincinnati Reds

Dec. 20, 2014: San Francisco Giants trade RHP Luis Castillo, RHP Kendry Flores to the Miami Marlins in exchange for 3B Casey McGehee.

Jan. 19, 2017: Miami Marlins trade RHP Luis Castillo, RHP Austin Brice, OF Zeek White to the Cincinnati Reds in exchange for RHP Dan Straily.

The San Francisco Giants didn't know what they had when they included a 22-year-old Luis Castillo alongside highly regarded pitching prospect Kendry Flores to acquire third baseman Casey McGehee from the Miami Marlins.

However, the Marlins had seen what he was capable of during a breakout 2016 season in the minors, and they still traded him away not once, but twice.

A deal that initially sent him to the San Diego Padres at the 2016 deadline fell apart when Colin Rea developed arm issues, and he was ultimately offered back to the Marlins in exchange for Rea as a re-do of sorts.

Despite the mulligan, the Marlins pulled the trigger on trading Castillo again that offseason, this time successfully sending him to the Cincinnati Reds in exchange for Dan Straily. The veteran right-hander would go on to post a 93 ERA+ in 304 innings before he was released prior to the 2019 season.

The same year he was released saw Castillo emerge as one of baseball's best young pitchers as he went 15-8 with a 3.40 ERA, 1.14 WHIP and 226 strikeouts in 190.2 innings to earn his first All-Star selection.

LHP Max Fried, Atlanta Braves

Dec. 19, 2014: San Diego Padres trade LHP Max Fried, OF Mallex Smith, IF Jace Peterson, OF Dustin Peterson to the Atlanta Braves for OF Justin Upton, RHP Aaron Northcraft.

The San Diego Padres had one of the busiest offseasons in MLB history leading up to the 2015 season, signing James Shields to a big contract in free agency while trading for Justin Upton, Matt Kemp, Wil Myers, Craig Kimbrel and Derek Norris.

The end result was a 74-88 record and several notable prospects lost in the process.

Left-hander Max Fried was the first high school pitcher off the board in 2012 as the No. 7 overall pick, and he had climbed to No. 53 on the Baseball America top-100 list at the start of the 2014 season.

However, he had undergone Tommy John surgery in August 2014, which may explain why the Padres were willing to part with him in the Upton deal.

The risk has paid huge dividends for the Braves.

The 27-year-old broke through as a full-time member of the Atlanta rotation in 2019 when he went 17-6 with a 4.02 ERA and 173 strikeouts in 165.2 innings, and he took his game to another level this past season to emerge as the ace of the staff and finish fifth in National League Cy Young voting.

LHP Josh Hader, Milwaukee Brewers

July 31, 2013: Baltimore Orioles trade LHP Josh Hader, OF L.J. Hoes, Competitive Balance Round A pick to the Houston Astros in exchange for RHP Bud Norris.

July 30, 2015: Houston Astros trade LHP Josh Hader, RHP Adrian Houser, OF Domingo Santana, OF Brett Phillips to the Milwaukee Brewers in exchange for CF Carlos Gomez, RHP Mike Fiers, cash.

One of two players on this list who was traded multiple times before finally making his MLB debut, Josh Hader was originally a 19th-round pick by the Baltimore Orioles in the 2012 draft.

After joining the Houston Astros in a 2013 deadline trade, his swing-and-miss stuff put him on the prospect radar, and he checked in as the No. 10 prospect in the Houston system at the start of 2015.

Questions about his command clouded his long-term outlook as a starter and kept him off the leaguewide top-prospect radar, and he was something of a throw-in alongside Domingo Santana and Brett Phillips in the blockbuster deal that sent Carlos Gomez to Houston at the 2015 deadline.

Hader then promptly exploded in the Milwaukee system, racking up 161 strikeouts in 128 innings while posting a 3.29 ERA in 126 innings between Double-A and Triple-A.

He debuted the following season in the bullpen and has quickly developed into the most overpowering reliever in the game, striking out 46.4 percent of the batters he's faced the past three seasons.

RHP Kyle Hendricks, Chicago Cubs

July 31, 2012: Texas Rangers trade RHP Kyle Hendricks, 3B Christian Villanueva to the Chicago Cubs in exchange for RHP Ryan Dempster.

If the Los Angeles Dodgers had been willing to include Allen Webster in trade talks with the Chicago Cubs, Kyle Hendricks likely never would have found his way to the North Side of Chicago.

Veteran Ryan Dempster was the top rental arm on the market in 2012, and he had made it clear the Dodgers were his preferred landing spot. But when the two sides couldn't agree to terms, the Cubs pivoted to a trade with the Texas Rangers.

Third base prospect Christian Villanueva—the No. 100 prospect in baseball at the start of the 2012 season—was the centerpiece of the return package alongside a soft-tossing High-A starter named Kyle Hendricks.

Hendricks made an immediate splash in the Cubs system, winning Minor League Pitcher of the Year for the organization in 2013 when he went 13-4 with a 2.00 ERA and 1.06 WHIP in 166.1 innings between Double-A and Triple-A.

His MLB debut came the following year, and he quickly cemented his place as a staple in the starting rotation.

The 31-year-old is now 69-48 with a 3.12 ERA (133 ERA+) and 1.11 WHIP in 1,047.1 innings over seven seasons with the Cubs, and he has already etched his place as a legend in franchise history thanks to his contributions to the club's 2016 World Series title.

LF Eloy Jimenez, Chicago White Sox

July 13, 2017: Chicago Cubs trade LF Eloy Jimenez, RHP Dylan Cease, IF Bryant Flete, 1B Matt Rose to the Chicago White Sox in exchange for LHP Jose Quintana.

The Chicago Cubs knew exactly what they had in Eloy Jimenez when they shipped him to the crosstown Chicago White Sox at the 2017 trade deadline.

He was the marquee prospect on the 2013 international market when he signed for $2.8 million, and he was fresh off a breakout 2016 season in which he hit .329/.369/.532 with 40 doubles, 14 home runs and 81 RBI in 112 games as a 19-year-old at Single-A.

However, with their title window still wide open and a glaring need in the starting rotation, Jose Quintana had a chance to be the missing piece for the Cubs to defend their World Series crown.

It didn't work out that way. Quintana is now a member of the Los Angeles Angels after walking in free agency, while Jimenez has only scratched the surface of his superstar potential on the South Side.

The 24-year-old launched 31 home runs as a rookie in 2019, and he won his first Silver Slugger Award this past season when he hit .296/.332/.559 with 14 home runs and 41 RBI in 55 games.

LHP Jesus Luzardo, Oakland Athletics

July 16, 2017: Washington Nationals trade LHP Jesus Luzardo, IF Sheldon Neuse, RHP Blake Treinen to the Oakland Athletics in exchange for LHP Sean Doolittle, RHP Ryan Madson.

Desperate for bullpen help, the Washington Nationals paid a steep price to acquire Sean Doolittle and Ryan Madson from the Oakland Athletics at the 2017 trade deadline.

Sinkerballer Blake Treinen had a 5.73 ERA in 37 appearances at the time of the trade, but he immediately righted the ship in Oakland. The following year, he put together one of the most dominant seasons in MLB history by a relief pitcher.

Meanwhile, left-hander Jesus Luzardo shot to the top of the Oakland farm system in 2018, flashing future ace potential while going 10-5 with a 2.88 ERA, 1.09 WHIP and 129 strikeouts in 109.1 innings. He reached Triple-A before his 21st birthday.

Still just 23 years old, he has one of the highest ceilings of any young starter in baseball, and he could get the first of many Opening Day starts in 2021.

SS Fernando Tatis Jr., San Diego Padres

June 4, 2016: Chicago White Sox trade SS Fernando Tatis Jr., RHP Erik Johnson to the San Diego Padres in exchange for RHP James Shields, cash.

Chicago White Sox general manager Rick Hahn has done a fantastic job building a contender from the ground up on the South Side, and their 2020 postseason appearance is just the start.

That said, this trade almost certainly still keeps him up at night.

The White Sox were 29-27 when they traded a 17-year-old Fernando Tatis Jr. to the San Diego Padres prior to his pro debut in exchange for veteran right-hander James Shields.

The 34-year-old went 4-12 with a 6.77 ERA in 22 starts the rest of the way, and the White Sox finished below .500 and missed the postseason. Signed for two more years, Shields ended up pitching to a 5.31 ERA in 436 innings while the White Sox paid $27 million of his contract.

Tatis made his pro debut during the second half of 2016 and then exploded the following year to rocket up leaguewide prospect lists. He made his MLB debut shortly after his 20th birthday and has quickly developed into a star for a San Diego team on the rise.

The White Sox have a good shortstop of their own in Tim Anderson, but this still has a chance to go down as one of the worst trades in MLB history before all is said and done.

SS Gleyber Torres, New York Yankees

July 25, 2016: Chicago Cubs trade SS Gleyber Torres, OF Billy McKinney, OF Rashad Crawford, RHP Adam Warren to the New York Yankees in exchange for LHP Aroldis Chapman.

The Chicago Cubs wouldn't have won the 2016 World Series without the addition of Aroldis Chapman to the back of their bullpen, so this is a trade they would make 10 times out of 10 even with the benefit of hindsight.

That doesn't make it any easier to see a former top prospect thriving elsewhere, especially considering Chapman made his way back to the New York Yankees in free agency just a few months after he was traded to the Cubs.

Gleyber Torres has something to prove after posting a 102 OPS+ with just three home runs in 160 plate appearances while struggling defensively at shortstop during a 0.0 WAR season in 2020. However, he's still just 24 years old and is only a year removed from posting a 127 OPS+ and launching 38 home runs to finish 17th in AL MVP balloting.

A full-time move to second base might be needed eventually, but his bat makes him a long-term foundational piece for the Yankees.

SS Trea Turner, Washington Nationals

June 14, 2015: San Diego Padres trade SS Trea Turner to the Washington Nationals as a player to be named in a three-team, 11-player deal completed on Dec. 19, 2014.

The Washington Nationals' portion of this trade seemed like highway robbery at the time, and that hasn't changed years later.

The main part of this three-team blockbuster deal saw 2013 AL Rookie of the Year Wil Myers traded to the San Diego Padres for a haul of prospects.

The Nationals simply jumped in as minor players and flipped outfielder Steven Souza Jr. and left-hander Travis Ott to the Tampa Bay Rays in exchange for right-hander Joe Ross and 2014 first-round pick Trea Turner, a return that seemed extremely lopsided even at the time.

Turner could not officially be included in the deal since he had not yet spent a full year in the San Diego organization—a rule that has since been changed as a direct result of this trade—and he began the 2015 season as a lame duck in the San Diego system.

He immediately became the shortstop of the future upon officially joining the Nationals and debuted just a few months after the trade was completed. He was the runner-up in NL Rookie of the Year voting in 2016, primarily playing center field before stepping into the everyday shortstop role the following year.

Still just 27, he led the NL in hits (78) while batting .335/.394/.588 and showing a new level of power with 12 home runs in 259 plate appearances en route to a seventh-place finish in NL MVP voting in 2020.

There's still room for him to take another step forward, and he's already one of the best shortstops in the game.

All stats courtesy of Baseball Reference.