I don't think lack of speed is necessarily a negative. However, if you don't have good closing speed, you have to be in the right positions at all times. For example, Per Mertesacker, who plays for Arsenal and Germany, is typically the slowest player on the field. However, his positional awareness is superb, so he doesn't have to cover ground as quickly. If the US back line can play smart and as a unit, I think we can defend well against most teams we'll play. I'm more concerned about teams like Portugal and Germany that are technically sound, have great movement off the ball, and play a quick, one-touch passing game, a la Barca.