Burdisso is not mediocre. He had a great season at Roma. Him and Juan were really class last term.
At inter, he fought against W. Samuel one of the best CB in the world, and that often led to being used as a right og left back, which is not hes best position.
But he is to expensive to be a backup, and really, he derserve to be a sterter, but he aint gonna get that with Inter.