Their defence is of a standard that more or less matches their ambitions and Jol does at least try to get his team to defend.
It's not like Roma, with their ambitions to compete for the scudetto with players like Kjaer at the heart of the defence and who continually allow forwards to run through on goal one-on-one with the keeper.
From speaking to Roma fans, a lot of their views of Stekelenburg were formed by him getting a few red cards due to him having to try and cover for his hopeless defence - not red cards that I would really blame a keeper for getting.