I'm not sure she was clueless. I just think a lot of the time people on that feel like they don't want to have an opinion or press the buzzer in the fear of getting it wrong. Probably didn't help her cause that Harmison is a bit of a QoS pro, and O'Shea knew a lot too.
Harmison even beat her to the buzzer on the Navratilova question.
For me, Question of Sport went seriously downhill when they ditched the non-multiple-choice what happened next round. That used to be one of the few truly laugh out loud things on telly.