Although it's general consensus that the team's strengths lie in goal and the midfield, not much consensus exists over who plays alongside Michael Bradley in the central midfield.
Many fans have recently started vouching for Jose Torres to start, but there is really only one player who should start alongside Bradley—Ricardo Clark.
It's a shame that Jermaine Jones couldn't recover from him shin injury quickly enough to make the World Cup squad, because he would have been a lock to start alongside Bradley in the midfield.
The best teams all have one great defensive midfielder protecting the back-line—Gilberto Silva with Brazil, Patrick Vieira with France, Esteban Cambiasso with Argentina (my implicit criticism of Maradona), etc.—and Jones could have provided something close for the national team.
Clark, fortunately, offers a similar defensive tenacity, bite, and enforcer quality that will protect our defense. While Bradley also is effective defensively, he is also perhaps our best—and only—box-to-box midfielder.
Clark's presence will springboard Bradley to make forward runs, utilize his passing abilities, and open up our attack.
When you consider who the United States will matchup with in its first few World Cup matches, the case for Clark should be all the more clear.
The United States will never be able to out-possess superior technical teams such as England and Spain, and must play accordingly. American players can't pretend to play like the Spanish and expect Spanish-like results (oh the irony). Against England, the US will plan around hassling Wayne Rooney and containing Frank Lampard and Steven Gerrard.
The importance of a solid defensive midfielder is magnified when we consider the tendencies of England's top players—Rooney likes to drop deep to collect the ball, while Gerrard and Lampard both like to move forward and control the center attacking space.
Both Clark and Bradley will need to be alert and clamp down this middle zone, both to nullify England's playmakers and force the Three Lions to play a more predictable game down the wings. Even if Peter Crouch plays, I'd take our chances with that sort of England game.
Furthermore, since Gerrard and Lampard both like to move forward, the additional cover provided by Clark will allow Bradley to move around and exploit open space. Since we will play a counter-attacking game, open space equates to opportunities.
If Capello plays a 4-2-3-1 with a fit Garreth Barry (or Parker should he have been chosen on the squad) in midfield and Gerrard as a support striker, Clark would be needed. If he plays a 4-4-2 with Gerrard and Lampard in the middle, Clark would provide the defensive cover needed to allow Bradley to make plays.
All-in-all, Clark is a more-established player than his fellow midfield competitors, and that should see him in the Starting XI against England and beyond.
Torres may be an extremely talented player who can do great things for the national team in the future (and put in an amazing performance that changed the game dynamic against Turkey), but Clark will help us beat England more than Torres will.