As of recent history the Brewers have generally favored bats over pitchers, drafting Trent Grisham in 2015, Corey Ray in 2016, and Keston Hiura in 2017. Some bats that I can see them considering for pick 21 are:
Connor Scott, OF- In the past few years the Brewers have put a lot of focus in acquiring and developing up-the-middle players, and they may envision a similar plan with Connor Scott, who is a toolsy prep bat with the potential to develop at least solid tools across the board. With the Brewers farm system taking a hit after acquiring Christian Yelich, taking high-ceiling prep bat could be a good step towards strengthening it again.
Brice Turang, SS- Continuing with the theme of up-the-middle prep talent, Brice Turang brings solid tools across the board at a premium position. While he doesn't have a standout tool, according to his scouting report on MLB.com, just having solid tools should make him a valuable player down the road if he is able to stick in SS.
Trevor Larnach, OF- This is a name that I've seen thrown around a few times when it comes to potential Brewers picks. Deviating a little from the Brewers' tendencies, Larnach seems more like a future corner outfielder than CF. However, he has the bat to profile well in either corner outfield positions.
Xavier Edwards, SS- Edwards seems like the antithesis of the stereotypical Brewers bat- not much of a home run threat, but makes good use of his contact-oriented approach and his plus speed. This doesn't mean that he would be at a disadvantage, however. Edwards can become a valuable table-setter hitting in front of some of the Brewers more powerful bats. On top of that, he is also able to play at a premium up-the-middle position- something that the Brewers have shown to value.
If the Brewers do decide to deviate from the pattern and pursue a pitcher, here are some pitchers that they may consider at pick 21:
Jackson Kowar, RHP- Kowar is a live arm from Florida, and what actually intrigues me about him is that he actually has a plus changeup. At least from what I remember, the Brewers haven't had many pitchers with plus changeup, if they were able to successfully develop pitchers at all. While Kowar isn't a finished product yet, he has the potential to develop into a solid starter for the Brew Crew.
Grayson Rodriguez, RHP- Rodriguez is a big kid with a big fastball along with promising secondary pitches. While the Brewers have leaned more towards the "get the bats early and find pitching later" philosophy, Rodriguez certainly has the talent to at least be worth consideration for their first pick.
Shane McClanahan, LHP- Personally, I highly doubt he'll drop this far. However, I did see him being mentioned as a potential Brewers pick in the most recent MLB.com mock draft, so I at least think it's an interesting possibility to entertain. Lefties that can hit triple-digits don't grow on trees, and if he somehow does drop to the Brewers' pick, I would imagine that he would be a very tempting pick.
And that concludes the second MOD for the Brewers. As always, if you guys have any other names that could be in the running for this pick, then feel free to discuss.