Jackie Robinson broke the color barrier in 1947 to usher in a historic moment for civil rights, yet Black representation in Major League Baseball stands at the lowest level since the 1950s. MLB initiatives have increased the number of Black players taken with top draft picks since 2010 – but those draftees haven’t made their way up from the minors often enough to stop the decline in the number of Black players in the majors.

An exclusive new analysis of the minor leagues shows one factor stopping Black players from making the majors: there has been persistent bias against Black and Latino players since 1950, preventing them from playing at certain positions and rising through the ranks of the minors. Players of color with darker skin often moved to the outfield and suffered the most bias. Conversations with former players, scouts, front office analysts, and baseball historians confirm those findings, with some recalling instances of overt bias even within the last 20 years.

Mitchell Nathanson, a law professor at Villanova and baseball historian, wrote a 2024 book called Under Jackie’s Shadow on the racism that Black minor leaguers faced from around 1950-1970. The book collects accounts from 13 Black players who came up through extraordinary barriers and often saw their careers ended or shortened by bias.

“I think that white people like a validating, happy ending to a story. So they’ll read about Willie Mays and Hank Aaron, because those stories end up with the players in the Hall of Fame – they succeeded,” Nathanson said.

“So you can kind of separate yourself from that, right? Because: ‘Oh it was this horrible thing that happened, but look what happened after: They persevered.’ Isn’t this a great American story? Well, that’s bullshit. Yes, those players are fantastic players, but that doesn’t justify any of the treatment they received. And it also ignores all the other players who didn’t have that level of talent and whose lives were ruined by this.”

Despite baseball’s emphasis on statistical analysis, there is no public database of race or ethnicity information about its players, so racial biases have proven hard to analyze. Using the racial classifications of 11,000 major league players painstakingly collected by hand by baseball researchers Mark Armour and Dan Levitt, I built an artificial intelligence model based on players’ faces and names to identify their perceived race. While the model could not say how a player might self-identify, it predicted how an outside human research assistant would guess their racial background about as accurately (94%) as another human would. I ran the model on all players with headshots and names in major and minor league history from 1950 to 2019, which amounted to about 40,000 players.

Teams usually start recently drafted players in the low minors, and the plan is that they slowly advance through six levels of increasing skill until they reach the majors (some players jump a few levels if they are good enough). After adjusting for hitting and fielding statistics, as well as the age of the players and where in the draft they were selected, I discovered teams were much less likely to promote Black and Latino players to the next level of the minors, even when they had nearly identical playing records as white counterparts. Statistics show that, since 1950, once Black and Latino players make the majors, they outproduce their white colleagues, demonstrating that this bias is not justified by their results on the field.

One of the players who joined the minors in the wake of Jackie Robinson’s achievement was Ron Allen, who worked his way up to a short spell in the majors in 1972. Allen comes from a baseball family. One of his brothers, Dick, is arguably the best third basemen in baseball history not to make the Hall of Fame. Ron’s oldest brother, Hank, was a longtime scout for the Houston Astros through 2017 and a successful MLB player in his own right. Both Dick and Hank died recently. All three came through the minors in the heart of the civil rights era.

“It didn’t make no difference if I hit .300 and [a white player] hit .270, he was gonna be moved ahead of me,” Allen said.

Allen is right: the effect of racial bias was large. The disadvantage Black players faced was comparable to having an On-Base plus Slugging (OPS, an all-inclusive hitting metric) about 35 points lower than they actually had – or about the difference between the offenses of the Houston Astros and the St Louis Cardinals, who had the 11th best and 15th best records in baseball respectively this year. This effect also stayed the same from 2000-2019 compared to 1950-2000: Black and Latino players are still promoted less than their performances would indicate they should be, based on a statistical model predicting promotions. MLB declined to comment on the results of this study.

There was also a correlation among Black and Latino players between the physical color of a player’s skin and whether they moved up to the next level of the minors. I took the color of a player’s skin from their roster headshot, and measured the color by putting it on a quantitative scale from black to white. The impact of going from a relatively light-skinned Black or Latino player (at the 25th percentile of skin color) to a darker-skinned player (at the 75th percentile) was approximately 40 points of OPS.

Though the disadvantage was measurable and significant, a 10-20% handicap in promotion rate wasn’t usually enough to stop all-time greats from making the majors. Players like Aaron, Mays, and Roy Campanella, as well as many other pioneers of the era, were so much better than their competition that a bias against them was a speed bump, not a roadblock. But for more marginal players, those without Hall of Fame talent, it could end their careers, especially when combined with other forms of bias, like teams channeling Black and Latino players to certain positions.

Some of the greatest Black players throughout baseball history have patrolled the outfield, from Aaron to Mays to Aaron Judge. Yet there are comparatively fewer Black players at other spots on the diamond such as catcher, second base, third base, and starting pitcher, limiting the career prospects and earnings of talented Black players with the skills to play these positions.

Wil Aaron came up in 1971. While he was a skilled hitter and deft fielder at second base, his team forced him to transition to the outfield. (Wil is also Hank Aaron’s cousin.) Wil Aaron’s story is all too common. “These positions, second base, shortstop, pitcher and catcher, those are the control positions. Those are the quarterback positions,” he said.

Catchers were most often the victims of this bias. Before 2000, about 3% of players identified as Black in the minors were at catcher, compared to almost 10% of white players. Each year in the minors before 2000, Black catchers moved to other positions about 50% more often than white catchers, even though the Black players were hitting and fielding better than their white counterparts. Once moved to the outfield, however, teams shifted Black players from the outfield to other positions about half as often as white outfielders.

Unlike other sports where Black players have started to comprise a larger share of historically white positions – NFL quarterbacks are perhaps the most striking example – there has been little or no progress in recent years in baseball. The rate of Black catchers since 2000 has fallen to less than 2% in the minors, and the percentage of Black players in the outfield is at 47% – right where it was before 2000. Since 2000, there have been only a handful of full-time, every day Black catchers in MLB.

Among Black and Latino players, the lighter a player’s skin tone was, the more likely they were to play catcher or shortstop or pitcher. The darker a player’s skin tone, the more likely they were to play the outfield. Among white players, there were no significant differences in skin tone between players at different positions.

There are more Black pitchers after 2000, but there are more pitchers in general, due to strategic changes in the game, so the ratio of white to Black pitchers has remained the same. And Black and Latino pitchers are often relegated to middle relief, the least important and valued type of pitcher: they tended to have fewer games started and fewer saves than white pitchers, despite, on average, having a better strikeout to walk ratio and allowing fewer runs per opposing batter faced.

Some types of bias did disappear from the game after the civil rights era. In the early days after integration, opposing pitchers often tried to retaliate against Black players by hitting them with thrown pitches, as Robinson experienced. Over a 20-year period from 1950-1970, pitchers struck Black hitters in the minors twice as often as white players.

Opposing white pitchers often targeted Allen, and some years he had a hit-by-pitch rate over four times as high as the average. “Sometimes a catcher would warn you,” Allen said. “He would tell you: ‘Hang loose’. So that meant you were gonna get plunked.” The increased HBP rates declined by 1970 and Black and white HBP rates have been much closer since then.

Allen wasn’t surprised that racial bias around positions and promotions hadn’t disappeared in recent years. “I remember when Hank said to me one time when the movie was out, 42, about Jackie Robinson.” Allen said. “[Hank] said, ‘Man, I can’t watch that.’ And I said, ‘How come, Hank?’ He said, ‘Because we lived it, I can’t go through that again.’ And I started laughing. He said, ‘Oh, there’s nothing to laugh about!’ I said, ‘But you know, that’s behind us now, you know.’ He said, ‘No, it ain’t behind us, it’s still there.’”

While MLB’s player base has grown increasingly diverse in recent years, with sizable Latin American and Asian contingents, team management has continued to be overwhelmingly white, perhaps partly explaining why racial biases continue to exist. The Institute For Diversity And Ethics In Sport publishes reports on the demographics of MLB’s (and other sports’) leadership positions. In 2004, the earliest report listed on their website, there were seven Black or Latino managers; in 2023, there were six. Among senior front office members, 17% were people of color in 2004; in 2023, 21%. About 40% of MLB’s players are people of color.

As teams increasingly use statistical approaches to evaluate players that are intended to be blind to race and color, many front office employees expected that biases might begin to disappear. Ben Baumer, a former analyst for the Mets who is now a professor of statistical and data sciences at Smith College, noted that sabermetrics is not a cure-all for discrimination. Predictive algorithms trained on biased data – for example, where Black players often move to the outfield and don’t tend to make the majors as often due to bias – may learn to predict that players who recently switched to the outfield are less valuable prospects, echoing the bias in the data used to train them. “We’ve created a lot of the data science products at least in part with the idea that we would be removing bias by having machine learning algorithms,” Baumer said. “In a lot of cases, we’re actually amplifying the systemic inequalities that are present in the data.”

Front office sources both past and present agreed that there are often hidden stereotypes and coded language used to describe players based on their race. “How many non-white gamers have ever been named as a gamer?” said Fernando Perez, a former major leaguer who is now a coach with the San Francisco Giants. (A “gamer” is a clutch, reliable or especially competitive player.) Using a database of Cincinnati Reds amateur scouting reports from 1998-2003 originally reported on by the Ringer, I found obvious differences in how scouts described white, Black, and Latino players. Nine times out of 10, the words “gamer,” “leader,” and “great” or “good makeup,” were applied to white players (“makeup” refers to the mental aspect of the sport). Meanwhile, comments about “questionable” makeup, laziness, background, and even a player’s father or their hairstyle were all at least twice as likely to be applied to Black and Latino players. Two front office employees with different teams recalled separate instances of overt and explicit racial discrimination among influential front office employees and scouts, and the book Under Jackie’s Shadow contains a recent story of clearcut racial discrimination as well.

While some front office employees mentioned overt racism, others said that their teams made a proactive effort to recruit diverse talent and eliminate bias from their evaluations. Players and front office employees who had worked for multiple teams said that different front office cultures could have wildly divergent attitudes and tolerance for coded language and racial bias, and that some teams were genuinely progressive – and sometimes benefited by hiring players other teams might undervalue.

The impact of racial bias on those affected is enduring. In addition to the impact on players’ careers and livelihoods, research has shown that experiencing racial bias can harm health and psychological wellbeing in the long-term. “Can you believe this? I’m 72 years old, and I have nightmares … I’m running in uniform to catch the train, and the train is moving off down the track with the rest of the team on it,” Aaron said. “People are telling me, ‘Oh, just put it aside. Just forget about it. Let it go.’”

Aaron continued, “It’s hard to let go, man, when you’ve been done wrong.”

• Thanks to Brandon Smith for research assistance, and Mark Armour, Daniel Levitt, the Society for American Baseball Research (SABR), and Baseball Prospectus for providing key data.