He was a stop-gap signing at perhaps the only time under Wenger that we've been so badly understaffed with so little time to do anything. See also the rest of the guys who came in at the end of the same window. Santos obviously wasn't near the top of the scout recommendation list - like Mertesacker, like Benayoun - with probably the only attribute going in his favour being his tekkers. But tekkers can't cure obesity. There's no doubt they were stuck for options.