My thoughts are while not explicitly stated I think an apothecary should be able to be used to automatically "heal" a KO'd player, that has not previously recovered. I don't think this use is covered by the original rules, although its a little vague.
So I'm proposing that this be made explicit:
During a match, an Apothecary may attempt to cure a player
who has suffered a Casualty or been KO'd. An Apothecary can
be used only once per match. If the player was KO'd leave him
on the pitch Stunned or in the Reserves box if not on the pitch.
Otherwise immediately after the player suffers the Casualty, you
can use the Apothecary to make your opponent roll again on the
Casualty table (see page 25) and then you choose which of the
two results to apply. If the player is only Badly Hurt after this roll
(even if it was the original Casualty roll) the Apothecary has
managed to patch him up and pump him full of painkillers so that
the player may be moved into the Reserves box. Alternatively, at
kickoff an apothecary can be used to automatically recover
a KO'd player.