There are trades. And then there are those trades that have gone down in history as the most lopsided we've ever seen. Deals in sports are always won or lost in hindsight, but few have ever been as disproportionate in their results as the trade that sent slugging outfielder Frank Robinson from the Reds to the Orioles on Dec. 9, 1965.

Although it's been more than half a century since the transaction took place, it is no less stunning today than it was when it happened.

Here's a breakdown of the who, what, when, where and why of one of the all-time heists in MLB history:

The players

Robinson was traded from Cincinnati to Baltimore for pitchers Milt Pappas and Jack Baldschun and outfielder Dick Simpson.

Robinson was one of the game's greatest players -- he was the 1956 National League Rookie of the Year, the 1961 NL MVP, a six-time All-Star, and through his age-29 season he had 324 career home runs.

Pappas was the centerpiece in the trade from Cincinnati's perspective. The 26-year-old All-Star right-hander owned a 3.24 ERA over 264 appearances (232 starts) with Baltimore.

Baldschun was a good reliever with the Orioles -- at the time of the trade, the 29-year-old righty had posted a 3.18 ERA over 333 appearances in nine seasons.

Simpson was just 21 years old at the time of the trade and had spent the previous three seasons with the Angels before getting traded to Baltimore just seven days before being dealt to Cincinnati. At the time, he was a career .176/.276/.282 hitter in 35 Major League games.

Why did the deal happen?

Reds general manager Bill DeWitt was convinced that Robinson was past his prime at age 30. DeWitt said Robinson was "a fading talent increasingly hobbled by leg injuries," and "an old 30."

In an era in which starting pitching was heavily relied upon -- a stark contrast from today's game, in which bullpen specialization and an ever-increasing volume of data have led to fewer and fewer innings for starters -- the Reds had one starter with an above-average ERA+, Jim Maloney. Cincinnati went from having one of the best pitching staffs in baseball in 1964 to one of the worst in '65. So the Pappas and Baldschun additions certainly made sense from that angle. But, of course, there were two sides to the trade, and therein lies the reason it's being written about to this day.

From the perspectives of Orioles outgoing general manager Lee MacPhail and incoming GM Harry Dalton, the rationale was pretty simple -- they were getting Frank Robinson.

The aftermath

It didn't take long to see that the Orioles swung one of the greatest deals in MLB history when they acquired Robinson. In his first season with Baltimore, Robinson not only became the first player to win the MVP Award in both leagues, but he also became only the eighth player in the Live Ball Era to win the Triple Crown (two players have won it since) and led the O's to a World Series championship in a sweep of the Dodgers.

On the other side of the trade, none of the three players Cincinnati acquired were with the club by 1969. Pappas pitched two-plus season for the Reds, posting a 4.04 ERA over 490 innings before being dealt to the Braves in '68. Baldschun pitched to a 5.25 ERA over 51 appearances for the Reds from 1966-67 before arm issues led to a Minor League demotion and, eventually, a release in '69. Simpson hit .246/.335/.391 in 136 games between 1966-68, and was traded to St. Louis the following offseason.

Within one season, it was clear that the Orioles won this trade big, and it became even worse for the Reds when their acquisitions didn't perform. But Robinson wasn't nearly done making this deal look awful for Cincinnati -- he went on to hit .296/.399/.521 and slugged 130 more homers for Baltimore over the next four seasons.

Robinson actually posted a higher OPS+ (169) in his time with the O's than he did during his time with the Reds (150). He also smashed nine homers in 30 postseason games while in an Orioles uniform, being named the MVP of the 1966 World Series and also helping Baltimore reach the Fall Classic in each year from 1969-71, winning it all again -- in five games over his former team -- in '70.

The trade in numbers

Robinson with Orioles

Seasons: 6

WAR (Baseball Reference): 32.4

Salary: $539,000

Cost per WAR: $16,636

Pappas, Baldschun and Simpson with Reds

Seasons: 3

WAR: 5.4

Salary: $171,250*

Cost per WAR: $31,713*

*Salary information for Pappas and Baldschun are unavailable for their time with the Reds, so this calculation uses their respective salaries from their final season with the Orioles as an estimation.

An all-timer

When it comes to lopsided trades, you won't find many that beat the deal that sent Robinson to Baltimore. Even 56 years later, it's stunning when you look at the trade, both on paper and in the subsequent results. It turns out that Robinson wasn't, in fact, an "old 30." Or an old 33. Or an old 35.

Hindsight is 20-20. But in 2021, the Robinson transaction still rates as one of the greatest heists in MLB history.