Dan Luu has a good article on this: [1]

> A problem is that it's hard to separate out the effect of discrimination from confounding variables because it's hard to get good data on employee performance v. compensation over time. Luckily, there's one set of fields where that data is available: sports.

> ...

> In baseball, Gwartney and Haworth (1974) found that teams that discriminated less against non-white players in the decade following de-segregation performed better. Studies of later decades using “classical” productivity metrics mostly found that salaries equalize. However, Swartz (2014), using newer and more accurate metrics for productivity, found that Latino players are significantly underpaid for their productivity level. Compensation isn't the only way to discriminate -- Jibou (1988) found that black players had higher exit rates from baseball after controlling for age and performance. This should sound familiar to anyone who's wondered about exit rates in tech fields.

> ...

> In tech, some people are concerned that increasing diversity will "lower the bar", but in sports, which has a more competitive hiring market than tech, we saw the opposite, increasing diversity raised the level instead of lowering it because it means hiring people on their qualifications instead of on what they look like. I don't disagree with people who say that it would be absurd for tech companies to leave money on the table by not hiring qualified minorities. But this is exactly what we saw in the sports we looked at, where that's even more absurd due to the relative ease of quantifying performance. And yet, for decades, teams left huge amounts of money on the table by favoring white players (and, in the case of hockey, non-French Canadian players) who were, quite simply, less qualified than their peers. The world is an absurd place.

[1]: https://danluu.com/tech-discrimination/