Alex Jackson has superficially decent overall AAA stats, but I looked at his game logs and he has base hits in only 5 of his 12 games. For reference, Ryan Jeffers has had base hits in 11 of his 17 starts at catcher or DH, and that's against major leaguers.
Baseball averages are basically the "mean", and I've often wondered whether a second-order measure such as "standard deviation" would be revealing about certain players having uneven performances, but I've never invested the time to try to investigate.
Anyway, my working theory (lacking real analytics) is that Jackson is one of many hitters who knows how to feast against lesser opponents, with Plan A being "wait for your pitch," but who has no Plan B and flails when the opponent has the command to put his best stuff where he wants it time after time.
Last year's breakthrough at Baltimore appears to have been a mirage. If the need arises to bring Jackson up, I don't expect good results.
I realize this is a controversial take, not to mention answering a question no one has even brought up. 🙃