Definitely our Achilles-heel, though I have high hopes.
Van der Wiel has really improved, turned into one fine player. Heitinga is simply a much better player in the centre of defense than as RB, and that means we won't play Ooijer, which can only be a good thing. Mathijsen is pretty slow, but a decent defender.
LB is a different story, as vBronckhorst is our captain, but he's not fully fit. He quits football after this WC, so if fit, we'll probably play him. He's getting too old...
His injury might be a blessing in disguise though, as Anita, a young LB from Ajax who was called up for this training camp, apparently left an amazing impression on our coach and looks to make the cut into the final 23. It's risky, but Van Bronckhorst really isn't the same player he used to be.
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Yes, I'm a bit biased and optimistic, especially about the fullbacks, but I think we could be alright. It looks quite a bit stronger than the defense we've been fielding for the last few years though.