As a point of reference, when Trent Grisham was called up in 2019, he immediately went into the starting lineup in game 110, and played in 51 of the remaining 52 games and was a starter in 35 of them.
I really don't know why anyone suggests the manager "misuses" players on the Brewers roster. It flies in the face of seasons worth of contrary information. Believe your own eyes and use logic, the Brewers have tablets in the dugout with video on them, if they're that reliant on information its implausible the coaching staff isn't aware of player splits, player tendencies, matchups, etc. Thus, there is a reason why Hiura plays against the pitchers he does, and there is a reason the relief pitchers pitch when they do. Rather, it is an indictment of the quality of reporters on the Brewers beat (McCalvy, Rosiak, Sophia, etc). that they haven't asked the manager those "why" questions yet.
P.S.
Apparently one of those why questions was asked yesterday:
https://www.jsonline.com/story/sports/mlb/brewers/2022/08/17/why-hasnt-keston-hiura-been-milwaukee-brewers-lineup-more/10343102002/