Realizations of the Stance Adjunct: summary
Stance adjuncts can be realized by adverbs, prepositional phrases, finite and non-finite clauses:
Adverbs: surely, obviously, frankly, honestly, confidentially, hopefully, probably
PPs: in fact, in reality, at a rough guess, by any chance, of course
Non-fin cl: to be honest, to tell the truth, strictly speaking
Fin. cl: if I may be frank with you . . . ; don’t take this personally, but . . .