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)

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

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.