True, but that's just how it is. They have short memories. It was the same with Raul, Guti, Zidane, Brazilian Ronaldo and countless others. When these players do not perform to the level they are capable of they will get booed. It is a mixture of fans being spoilt and also knowing certain players can do better and give more than they are (Casillas refusing to admit that he has made mistakes in certain games like after the Atletico one has not helped with some fans either). Personally I think cheering, offering encouragement and getting behind players is more beneficial than booing but obviously a lot seem to disagree. That said, last season and the season before, when he was on the bench he got a lot of support from the fans and they cheered and chanted his name loudly after every save that he made in the CL games that he got to play last season despite Lopez doing well in his place. There was almost a campaign from the fans to get him playing over Lopez. So Casillas was given more patience and the benefit of the doubt for a longer period of time than most players would be afforded from Madrid fans whose patience generally runs thin very fast, but in the end I guess people are finding the mistakes (as well as some of his behaviour over the last few years) to be too much. He still does not deserved to be booed though and what fans are writing on forums in inexcusable.