by Ridge Mahoney @ridgemax, Jan 9, 2014

By Ridge Mahoney

Michael Bradley

Omar Gonzalez

Matt Besler

Clarence Goodson

Graham Zusi

Landon Donovan

Clint Dempsey, Eddie Johnson

Mix Diskerud

Brad Evans

Kyle Beckerman

Benny Feilhaber

Geoff Cameron

Jimmy Conrad

Jonathan Bornstein

More and more, the 2014 World Cup is shaping up as a referendum on a vital aspect of Major League Soccer.With the defection of midfielderfrom Roma of Serie A to Toronto FC of MLS, nearly one-half of the U.S. national team’s pool of regulars is based domestically. The top three centerbacks (), at least two essential midfielders (Bradley,), and three of its primary attackers () will, like all of their January camp mates except Norway-based, be housed at home this year. Throw inand, who are not as assured of a spot on the World Cup roster yet likely to be included, and that's a hefty MLS contingent of players high on the depth chart.Dempsey’s arrival last summer, along with that of Goodson, and the impending Bradley move have occurred critically close to the World Cup, and so their MLS form in the weeks leading up to their departure for World Cup training camp in early May will be closely scrutinized. Yet all of those players have spent years in European soccer as well as with the national team; they have enough experience to self-monitor their levels of fitness and form leading up to a World Cup.They’ll have a keen sense, as will head coach Jurgen Klinsmann, of where they stand as March and April unfold. They’ve been through it before. They’ll know where they stand in relationship to what a World Cup requires. Barring injury, two months of MLS games won’t greatly affect their status.But I would cite those players who have not played in a World Cup nor in Europe as more relevant to provide the clearest barometer by which to rate MLS. A possible central pairing of Besler and Gonzalez, along with the anticipated contributions of Zusi -- possibly off the bench, a role at which another transplant,, excelled in 2010 -- is sure to be enlightening, since at this time last year all three were just getting established in the national team. Evans and Beckerman have been around longer but only under Klinsmann have their credentials been stamped. Aside from a few friendlies, Concacaf and MLS are all they know at the pro level.Goodson’s European experience and solid showings in several games last year give him a shot at unseating one of the regular centerbacks, but it’s quite likely the MLS-developed duo of Besler and Gonzalez will get the nod. (For this discussions of centerbacks we exclude, since most of the time that’s what Klinsmann does when the subject comes up.)One of Klinsmann’s most critical tasks leading up to the World Cup is sharpening and toughening that defensive core. Tenets of technical skill and possession play can’t be applied if the back line teeters, and while Besler and Gonzalez do fit the bill on the ball, stopping the opposition comes first. Relying on a pair of domestics seems risky, but both have excelled since coming to MLS out of college, and they will be in their sixth year of pro ball when they head to Brazil. They will be the acid test of what MLS and U.S. Soccer have developed within U.S. borders, and now their primary conduit through midfield, Bradley, is also based domestically.And don’t downplay the importance of backups.(2006) and(2010), both MLS lifers at the time, were critical factors when called into action. Since he took over the national team Klinsmann has stressed that every player named on a lineup sheet has to be fit enough and good enough to start or come off the bench. He’s also been clear that players should seek out tougher challenges, but the retro moves of Goodson, Dempsey, and Bradley run counter to that dictum.In the steaming cauldron that is a World Cup game, selection mistakes are costly, as the Americans discovered four years ago in the round of 16 against Ghana. Next June, Zusi might be a second-half sub if the Americans need a goal, and Evans’ versatility could land him a spot. Feilhaber helped SKC win a league title a month ago and is in camp this week.Bradley’s pending transfer occurs a week after Dempsey’s loan to Fulham took effect. That move was loudly applauded by the national team head coach, who reacted frostily last summer when Dempsey signed with Seattle. Now perhaps his most important player is based domestically. During the next five months dynamics within the national team will change dramatically and only in Brazil can certain crucial aspects of MLS be judged.