The most important thing about being a defender is one's defensive abilities, all values are the average per game:
The first three, especially the first two, are the most important; they show tangible defensive work, in this regard the ex-Arsenal and current Arsenal left-backs are the best. Blocked shots are also important, but all the players are relatively close. At first glance, clearances might seem important, but they could actually be something negative: the players that clear the ball the least, are passing the ball out the most; although goal-line clearances and headering crossses away are obviously good.
The last thing to look at is attacking ability. Full-backs are used more and more in setting up goals, especially in the teams that these players belong to. Actual numbers of goals and assists are in brackets. Leighton Baines actually had 2.8 successful crosses per game, and was fouled 1.5 tmes per game. But with those values included it was almost impossible to differentiate beween the other players (the colours are already quite similar).
According to the statistics Ashley Cole had a terrible season, but this is not really a true eflection of how he performed. Gibbs held his own throughout and is at a similar level to other players in his position. I was especially pleased at his defensive statistics, Podolski sometimes leaves him to defend by himself, but the Englishman has not let the team down. Hopefully he can continue to grow and develop as a player.