Like Miakisu said, I wouldn't go so far as 'make fun of' the person, and def not use their name - but rather use them as a teaching lesson example of what not to do.
ex, 'This monk gives us an example of what not to do as a DPS, [insert reason]" then use it to describe what it does/is doing to the party when someone does exactly that. IE, using the circumstance as a teaching tool rather than to point and laugh o_Oa