Brewer's impact on the short passing game could be huge. Group him with Jonnu Smith and Alex Ingold with three get-open-quick YAC WR/scatbacks. These agile blockers with the ability to hit 2nd level targets while moving can be game changing. If it's working, defenses may need to use less hands in a dirt defenders against a 2-1 formation.
The offensive line roster may be tackle heavy and continuity may be a goal. Eich, Kion Smith, and Ryan Hayes may be top 8 linemen that need playing time. If they bring back Lamm and draft a potential Armstead replacement, then it's unlikely there is a separate team athletic profile for the guard position.
The 49ers had some plays where Trent Williams lined up in the backfield. Brewer seems ideal as a move piece when going to a heavy 6 OL formation. Game situations throughout the season can favor a rotation of OL. For instance, there's no need to have Armstead on the field to run the clock down against a weaker team. Short yardage may need bigger players for a push, come from behind 4th quarter may need the best pass protectors, etc. Defenses have used multiple position players and those better a game situations, which may offer an offensive coach that likes to break with conventional wisdom an opportunity to tinker.