He made some errors in few matches last season particularly at the beginning, has been slated since. For me, the best defender we have and one of the best in PL. The one problem he has is he does not shout/talk and organize the back line. The type of game we play requires the defense to be dynamic, moving up and down- the offside traps are crucial. Kos is brilliant at reading and positioning as he is with other attributes, how ever since Cole left we have not too many left backs who are that great, many a time its has been the left side which has played the players on as has Squid and DJ. In Per he has finally found some one who is not a liability in terms of movement and positioning but as seen against Chelsea in the first half Santos and DJ held him out to dry more than a few times. Per is a decent defender who made two poor judgments against Chelsea but then i have seen Vidic making them too. In Kos, Vermaelen and Per we have 3 top CH's, in Sagna and Jenko we have very capable right backs its is left back which looks the problem, that said i don't think Santos has completely gelled and he looks like a real good one.