Tech firms underperform massively on this metric compared to other local industries (law, accounting, general Fortune 500s like Home Depot/Delta/UPS).
That said, tech firms in Atlanta in general have more African Americans than do similar firms in e.g. Austin or SV.
If I'm African American, Atlanta is a better place for me to get hired and promoted in tech than other tech hubs. My suspicion is that the fact that managers live in Atlanta normalizes for them the notion that African Americans can excel at white-collar work, so biases that exist everywhere are somewhat reduced here.