Lee Mack was not very interested in trying to make any actual stabs at answers, he was more interested in just being the 'funniest' on the show.
I hope NOT to see him on the show again. I will admit that Bill Bailey was also a bit juvenile on the last ep too, which also encouraged Alan to be so, but both of them usually have a much better idea of what the show is about.
I like Lee Mack in 'Not Going Out' but he does think he is funnier than he is.
What QI neeRAB is to return to having at least one proper 'brainiac' on the show like it used to be and less comedians there who think it is about how funny they can be.
I am pretty sure the change happened before the move to BBC1 tho, so I am not one of those people complaining just because it moved - I am sure most people 'invent' the dumbing down issue because they have some pre-conceived idea that BBC2 is automatically more high-brow so the dumbing down is some kind of inevitability.
But please, NO more Lee Mack on QI.