It’s to be expected that every once in a while everyone will make a bad hiring decision. Stuff happens. The important thing is not to inflict further damage by trying to salvage the situation. It’s much easier to fire a person on their first or third day than on the 30th. You’ve got to weed out the underperformers right away. You can’t bury them under mulch. You have to pull them out quickly before their roots go deep.
(Need a great speaker for your next meeting?)