Alright, against my better judgment, I will bite. Let's break down the current pool of defenders and compare it to the known players who are USMNT eligible and currently under pro contract and project their roles with the USMNT 3 years from now in Russia.
Don't confuse a lack of salary with a lack of talent. MLS artificially depresses salaries. Some of these players want to/need to remain in the USA and make what is available, not what they are worth. They also face discrimination in Europe based on their nationality and perceptions about the overall talent pool in the USA.
First, you mention Geoff Cameron. I don't know if you fit into this category, but plenty of people were calling him a donkey pretender just 3 years ago while he played for peanuts in MLS and people like me were screaming to get him in the pool. Then he goes to the bottom of the EPL on a free transfer and suddenly he is some gifted stud. Stuart Holden fits into this same category. MLS nobody. Goes on free transfer. Gets named MVP of his EPL club. The talent and potential didnt just explode over night. It was always there. Jay DeMerit. Same thing. Bob Bradley doesnt sign him to a practice contract at Chicago Fire. He goes to the UK, plays pick up and pub league. His talent is eye popping. Three years later he is in the EPL. Again, the talent was there, the chance wasn't. It doesnt make them less of an option for the USA. Back to Cameron, He's the same player he was with the Dynamo with a few rough edges polished, except he will turn 33 in Russia. You can have a 33 year old limping around back there, but I would prefer him as a locker room guy at best. He will be that cycle's Jermaine Jones. Versatile player with a lot of experience that is now a step slow and looking to use the 2018 team as a vehicle to extend his career back in MLS.
Fabian Johnson. He will be 31. Again, aging but still serviceable at his natural position of right back, if anybody would play him there. He is a starter for a legendary team in the top flight of Germany.
Ventura Alvarado. He will be 25. He will be in prime world cup age position. He has good range and can take care of business inside, when he has a good partner. He's playing at the top level in Mexico for one of the biggest clubs in the world. He will be in Europe be 2018. He's made a lot of young mistakes back there, but that is more a communication issue with Guzan, covering for Yedlin, and having a different partner in the middle every game, than it is talent or potential.
Matt Besler. He will be 31. Again, aging, but still serviceable in the middle at least for CONCACAF qualifying. Who he pairs with determines how well he shows. He stinks when back there with Brad Evans playing out of position. He's looked great working with Omar and Cameron. He covered a lot for Alvarado. Undersized at 5'11" for what we ask our guys in the center to do, especially on set pieces when we are playing negative. Here is the important point: He declined a free transfer to Fulham, QPR, Leeds, and several other major Championship clubs to stay in KC because his wife wants him there and Graham Zusi is his best friend. If QPR and Fulham think he is good enough to get them back into the EPL, then he is far from a donkey.
Matt Miazga. He will be 25. Long and lean at 6'4" and 180, he can run and jump like pegasus in a tail wind. He looks like a donkey because he is young and the eurosnobs assume he can't play because he is in the USA, but the truth is that he has been courted by the Polish national team since he was 10 or 12. He's played for their U18 and U20 teams. He plays in the USA because his parents are Polish immigrants and they want him to play here. And now he is cap tied to the USA. Poland's senior team desperately wanted him and they have their pick of top international talent training throughout Europe who are eligible for polish passports. He isn't a donkey. I predict he will be a starter in Russia. The tools and frame are there. The question is whether he will develop the strength to survive at the elite international level (Quarterfinal talent).
Michael Orozco. He will be 32. JK loves him and its easy to see why. As a young player, he was named to the all-tourney team for the 2008 Olympics. The team itself was terrible, but he outshined that and all the other defensive talent around the world. He can play inside and outside. If healthy and not a step slow, he will make it. He plays at Tijuana, but he isn't a donkey show. (Sorry, couldn't resist).
Brekken Shea. He will be 28. Prime time. I'm throwing him in here because he has played in the middle and on the left for both club and country at times. Has the physical tools to sign a free transfer with Stoke. Played both winger and defender for them before injuries and maturity issues sent him home. Not a donkey, at least talent wise. A bit of a head case. Talk to him for 30 seconds about his art projects and he will go off into neverland. JK loves him.
Tim Ream. He will be 31. Aging, but serviceable. Has played in the middle and on the left in both the EPL and the Championship. Voted MVP of Bolton by the fans. A donkey in the MLS until he went on a free to the Wanderers. Signed a four year deal with Fulham earlier this year. Will be back in the EPL next season and presumably in 2018. He's a legit international at two different defensive positions, but we have a coach that wants to use tactics that disfavor his positives.
Deandre Yedlin. He will be 25. To small and too short to fit into Klinsmann's plans on the right. He's got speed but can't defend worth a flip. I wonder if he will be in football by the time 2018 rolls around. Currently playing for Sunderland on loan from the EPL. Raw athletic talent that could contribute if the coaches used him correctly, but lacks the polish you need from a right back going forward and it is likely too late to develop it for him. I see JK losing patience with him. Your grandma's first touch is better, btw.
Shawn Berry. He will be 28. Plays in the German second division after a standout career at UVA. Done some U18 and U20 workouts, but no call ups. Played PDL, iirc. That probably means some conditioning or performance metrics aren't quite there for him. But, he's playing in the second tier of huge soccer country, so that tells you something. You wonder if JK will take a look in 2 years.
Rhett Bernstein. He will be 29. Plays in the top flight of Norway after Brown U. A couple of tourneys as U20, iirc, but nothing special. He can play inside or outside but a couple of inches short at 6 foot or so.
John Brooks. He will be 25. He has World Cup experience, including a goal scored, and he plays sporadically in the top flight of Germany. Far from a donkey. At 6'5" he isn't versatile, but he is the type of player who could develop into the best defender we've ever had. Or bust. Too early to tell.
Edgar Castillo. He will be 32. Plays in the top flight in Mexico. There if we need him on the left. International quality speed. Tracking back and communication can be an issue.
Timothy Chandler. He will be 29. Plays in the top league in Germany. Made the World Cup team, DNP. Not a donkey.