As TOPTB has alluded to, I'm not sure if Azpilicueta's crossing is better than Ivanovic's, maybe marginally better but not much. Having said that, I do agree with the notion that Azpi is a much better RB than Ivanovic is. If anything, the latter is generally good defensively as FB like Cole on the other side BUT Azpi can match that, if not better it, and provide a much progressive attacking play than Ivanovic. As seen quite a lot of times last season, Azpi moves the ball quicker, links up better with the wide players in front (similar to Bertrand and Hazard for instance on the left flank) and certainly has more variation in his attacking play than Ivanovic. And not to mention, Azpi certainly gets to the byline more often and has a left foot to work with if can't do anything with the right!