We aren't even talking about the brook we saw in his last fight. We are talking about a fighter already on the downward slope after lockdown, inactivity and further age / lifestyle? Related dulling of the reflexes.
To add to this, Williams also brings a high degree of risk, and is considerably fresher than Brook: he's a quality operator. Brook knows if he takes this fight and loses, then a potential final big payday he'd get for fighting Khan (which, in his myopia, seems to be the only fight Brook is interested in pursuing) goes up in smoke.
