Well, I think that's the question. I believe in 2021 Harper wasn't actually that much better than Castellanos (by DWAR or DRS). Both among the bottom three. And now he'll have had almost two years off, and will be two years older. He hasn't really been a good defensive OF since his first season in Philadelphia.
In a perfect world Rojas is such a defensive and baserunning weapon, with passable enough offense, that he goes to CF, and Marsh's hitting improves to where he's in the corner mix. Then you just have to make the platoon combos work to some extent.
And I think if they wanted to try Bohm in the OF they would have done that already. Never really understood why LF wasn't on the table, he's used to that side, he's tall, he's not completely immobile. But at this point I think the best case is he actually does hit well enough to either hold down 1B or continue to be tolerated at 3B. Worst case, he's not good enough to hang around into 2024 regardless.