Musharna changed somewhat since the RU drops. The shift of bulky offense to more aggressive offense meant Musharna can't Calm Mind as easily as it once did to easily decimate teams. It also has to keep an eye on its health so a certain ogre Pede doesn't spring out and skewer her. Even its STAB can be a conflicting choice: Psychic leaves you vulnerable to Jynx if Mushy doesn't have Signal Beam, whereas Psyshock doesn't have the special defense drop effect that could end stall wars and does pittance to Alomo, Torkoal and even Weezing. Mushy's speed also holds it back (much like Ferrothorn), as almost any Sub or Taunt in the tier can stop it from statusing and/or healing. Offensive sets can indeed catch opponents off guard, provided you can hide your lack of Leftovers or bluff the opponent at the expense of power from LO. In any case, Beheeyem still gives Mushy competition with Thunderbolt and Nasty Plot, which can deal with Mushy's newest nemesis in Mandibuzz. Of course, one does not simply forget about Mushy's infamous bulk, reliable recovery and great utility in Thunder Wave and Heal Bell, making it a great panic button in many situations. If we're still doing S-Rank subtiers I have no qualms having it put in Low-S.