Gabriele Marcotti: A dearth of quality center backs

Look around and note who's playing in central defense for the Champions League semifinalists. Barcelona? Gerard Pique, who is not having a good season, Carles Puyol, who is 34, and Javier Mascherano, who is 5' 9 and, until recently, a midfielder. Real Madrid? Pepe, OK, but then there's Sergio Ramos, a recycled right back and Ricardo Carvalho, 34 next month and often injured. Bayern? Holger Badstuber, Jerome Boateng, another recycled fullback, and Daniel Van Buyten, another sprightly 34 year old. Chelsea? David Luiz, who seemingly divides opinion like few others, Gary Cahill, who was playing for Bolton until December and John Terry, who needs no introduction when it comes to generating conflicting emotions. How many of the above can be described as "outstanding"?

How many are as good at what they do as their teammates who play up front?