There's some roster math they have to make some more opinionated decisions about soon. With 13 position players, you've got Happ, Bellinger, Seiya, Hoerner, Swanson, and Gomes as iron clad locks. For those remaining 7 spots, you've got non-optionable players with 2024 guarantees(Mancini, Barnhart), prospects that could use more playing time(Amaya, Morel, Mervis), and optionable role players who are playing well enough to earn their spot(Madrigal, Tauchman, Wisdom*). That makes 8, so with everyone healthy Mervis may stay down unless they do something they haven't yet been ready to do.
*Not currently playing well enough but has more significant history doing so than others
ETA: I don't have a great feel for this, but I'm wondering if July makes for a bit of a last stand for Wisdom. With Madrigal and Morel looking playable(plus the possibility of a trade target) he's more expendable if the bombs aren't flowing, and he's redundant with Mancini as a 1B/DH. They don't have to cut him as he has options, but if he gets sent to Iowa it's not hard to see him never coming back.