I fired off an email to the JTS Support email on this issue. I think that is should say this:
"When a non-Artillery unit attempts to change formation, then the Threat Value
in its hex is used to determine whether the change succeeds. If the change
fails, then the unit becomes Disordered or Routed."
When trying to change formation a unit can also Rout as well as Disorder if it fails the test. I am not sure where the boundary line is between Disorder outcome or a Rout outcome. The manual doesn't say.
_________________

Generalfeldmarschall Wilhelm Prinz Peters von Dennewitz
3. Husaren-Regiment, Reserve-Kavallerie, Preußischen Armee-Korps
Honarary CO of Garde-Ulanen Regiment, Garde-Grenadier Kavallerie
NWC Founding Member
For Club Games: I prefer the Single Phase mode of play. I prefer to play with the following options
OFF:
MDF, VP4LC, NRO, MTD, CMR, PR, MIM, NDM, OMR (ver 4.07)