If the Brewers "blew it" it was by the organization not moving Black away from the infield earlier. He was never that great of a hitting prospect. His 2021 season in A as a 20 year old was not that great. His 2022 as a 21 year old in A+ was better but he was really a man among boys so his wRC+ of 137 with only an ISO of .143 was more of "still a prospect" than we have a new top guy.
it wasn't until 2023 when he hit AAA that he looked like he might have something. He was at an age that lined up with his level and had an iso above .200 in both AA and AAA. His walk rates and K rates were also very good. But he fell off and his lack of a defensive home is a serious problem. Fangrpahs full scouting reprot from last year goes into it:
Black is entertaining as hell to watch play baseball, but I am skeptical that he's going to be the foundational young player that some folks across baseball think he'll be. He’s fast, he has a keen eye, he plays with lots of effort, and he swings hard for a small-ish guy. He slashed .284/.417/.513 across Double- and Triple-A in 2023 and raised his career minor league line ton excellent .279/.415/.465. For the last couple of years, Black (and my forecast for him) has been fumbling around for a defensive home. He has largely played second base during the last half decade and gave center field a try in 2022, but moved to third base in 2023 and even began to get some reps at first. He actually looked pretty good at third base aside from his throwing stroke, which sometimes looks odd and lacks accuracy. It's a big enough issue that I have him projected to first base and will speculate he'll eventually play the outfield corner, as well. Black's 2023 power output was likely a caricature of his true ability. His game is grounded in his contact and (more significantly) on-base skills. He lacks the power typical of a corner infielder and I also have some reservations about his ability to carry above-average contact rates to the big leagues. Black needs a ton of effort to swing hard and his head often flies all over the place. His swing also has a hole in it (up and away) that will be probed by big league fastballs until he proves he can close it. So no, I don't have Black evaluated as an everyday player. Because he's backed into a fair bit of defensive versatility, runs well, and has a plus-plus skill in his plate discipline, he'll still have roster utility as corner role player of modest impact
He was given a 40+ grade which is what he appears as right now. I still think he should be tried as a 1B/OF platoon bat until he shows he can or can not handle it. It's not like he would be blocking other superior options. As said above, give him the Bauers role until he takes off or loses it.