If you look at New York's drafts from 2002 to 2006, they brought in some decent talent, including seven players who've earned at least one US cap; however, the Red Bulls prioritized acquiring NASL-type veterans over keeping young prospects. As a result, following Reyna's retirement, their only remaining US internationals are second-stringers John Wolyniec and Zach Thornton. Contrast that with Houston, who've done their best to retain North American soccer players long-term and consequently won steadily.
Here's my attempt at a breakdown of all the active US internationals (nice to see how much our talent pool has grown, I count 102 of them) ...
Houston (9) - Barrett, Robinson, Boswell, Mulrooney,
Clark, Davis, Mullan, Ching, Jaqua
Chicago (7) - Busch, Brown, Gutierrez, Thorrington, Mapp, Rolfe, Barrett
Kansas City (6) - Hartman, Conrad, Zavagnin, Victorine, Arnaud, Wolff
Los Angeles (6) - Vanney, Klein, Vagenas, Franchino, Donovan, Buddle
New England (5) - Reis, Parkhurst, Albright, Ralston, Twellman
Colorado (5) - Petke, Ihemelu, Mastroeni, HGomez, Casey
DC (5) - Wells, Namoff, Simms, Olsen, Quaranta
Columbus (4) - Marshall, Hejduk, Carroll, Gaven
Chivas (4) - Bornstein, Marsch, Razov, Eskandarian
RSL (4) - Rimando, Borchers, Beckerman, Findley
San Jose (4) - Cannon, Garcia, Corrales, Kirovski
Toronto (4) - Dunivant, Wynne, Edu, Cunningham
Dallas (2) - Cooper, Moor
New York (2) - Wolyniec, Thornton
England, Prem (7) - Howard, Friedel, Guzan, Keller, Spector, Johnson, Dempsey
England, Chmp (6) - Hahnemann, Convey, Demerit, Simek, Feilhaber, Lewis
Unattached (4) - Hill, Mathis, McBride, Gibbs
Denmark (3) - Califf, Nguyen, White
Norway (3) - Goodson, West, Noonan
Germany, Bundes. (2) - Cherundolo, Zizzo
Germany, Zweit. (2) - Berhalter, Pearce
Spain (2) - Altidore, Szetela
Belgium (1) - Onyewu
France (1) - Bocanegra
Netherlands (1) - Bradley
Portugal (1) - Adu
Scotland (1) - Beasley
Sweden (1) - Davies
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