I agree, and the answer is "I don't know". But it's not because Wenger thought Fabianski was the next David Seaman.
Almunia was, at times, close to good enough I reckon - I think he was our 'keeper in 2007/8 when we were close to being Champions before the trademark collapse, and I don't think he was particularly at fault for the collapse. But then he went terrible.