Well, the 2014-15 season has been over for quite some time now and the Copa America is already in full swing, but that doesn't mean that we can't look back at an impressive year through some stats, once again supplied to us by the great folks over at Sports Matrix. Today we're going to focus on the effectiveness of the two sets of players that get the most attention when they make mistakes, though only one of them, usually, gets the praise when they help the team get win. And continuing with that (very) short description, let's first start with the former group, the quartet that has this season played in the heart of the defense - Gerard Pique, Javier Mascherano, Jeremy Mathieu and Marc Bartra.