He was a cost-savings, but not as big of one as we'd expected, given how big of a reach he looked to be:
The Braves saved $450k by picking him, which is part of what they moved down into the later rounds to sign guys like Tyler Owens, Joey Estes, Makhi Backstrom, Kadon Morton, et al—though about $300k went to signing Stephen Paolini at twice his slot (oops).
Fun fact: both Shea Langeliers and Michael Harris II signed underslot deals as part of this four-dimensional chessgame of a draft—the Braves saved a full $900k on the former and ~$40k on the latter—and also look to be the only two impact players drafted. Indeed, Stephen Paolini ended up earning about $100k more in signing bonus than Michael Harris II, thanks to Paolini's substantial overslot.