While it was difficult to leave out a few big names that burned oh so brightly for a brief time, we tended to favor those who remained top-shelf for a longer period.
It was no easy feat narrowing the the top shelf down to 10 names, so of course we had to offer up some very honorable mentions: Jeff Agoos, CJ Brown, Matt Hedges, Lubos Kubik, Alexi Lalas, Carlos Llamosa, Ryan Nelsen and Jamison Olave.
No. 10: Bobby Boswell
Few MLS players were as strong in the heart of defense as long as Boswell, who went nine years between his two Best XI appearances. Only two center backs have played more minutes than the Floridian, who may long be remembered in West London for his yeoman's effort in the MLS All-Stars' 1-0 victory over a star-studded Chelsea side back in 2006 (the same year he claimed Defender of the Year honors).
No. 9: Jimmy Conrad
The former San Jose and Kansas City defender was quite the character during his 12 seasons and change in MLS, and even more so a top-level gamer. Conrad was named to the Best XI four times and played in two MLS Cups, winning one.
No. 8: Michael Parkhurst
The ultimate brains-over-brawn defender has helped steer three different clubs to the MLS Cup final, finally winning it last season with Atlanta United. Parkhurst is so steady, both on and off the ball, that the degree to which he's underrated has long since become cliché.
No. 7: Matt Besler
If there's one other guy on this list whose game matches the boxes ticked by Marshall's, it's the Sporting stalwart. Now in his 11th season, the ultra-consistent Besler defends well on land or in the air and offers the ball safe passage out of danger. And like Marshall, he won just about every individual and team prize available, including three U.S. Open Cups.
No. 6: Marcelo Balboa
The US men's national team mainstay was the man who made defense exciting. Balboa never captured any personal awards or team trophies, but he was named to the league's All-Time XI in 2005 and captained a sub-.500 Colorado Rapids side to MLS Cup in 1997. The swashbuckler was also quite arguably the most offense-capable center back in MLS history; no one at the position had scored more league goals until Marshall passed him last season.
No. 5: Carlos Bocanegra
One of only two center backs to cop back-to-back Defender of the Year awards, Bocanegra easily makes the cut despite working only 136 league contests. Bocanegra was as foreboding as they come, racking up the 2000 Rookie of the Year award, twin Best XI mentions and two Open Cup crowns in four seasons with the Chicago Fire before heading off for a successful 11-year career in Europe.
No. 4: Omar Gonzalez
The longtime LA Galaxy air marshal might have challenged for the top three here had he not taken his game south of the border to Liga MX three-and-a-half years ago. In just seven MLS campaigns, the towering Gonzalez piled up four Bext XI nods, both a Defender of the Year and Rookie of the Year awards, three MLS Cup rings and a pair of Supporters’ Shield wins.
No. 3: Robin Fraser
No MLS defender can match the current Toronto FC assistant coach's five Bext XI honors. Fraser helped both the Galaxy and Columbus Crew SC claim their first-ever Supporters’ Shields. During the latter regular-season title run, he picked up his second Defender of the Year award while mentoring then-rookie Marshall. He also helped the Galaxy become the second (and to date last) MLS club to win the Concacaf crown in what was then called the Champions Cup.
No. 2: Eddie Pope
The original MLS smooth criminal may well have finished atop this list had he not spent so much time either in the injury ward or away on USMNT duty. An incredibly mobile tackle machine, Pope chalked up four Best XI nods (five if you include 2005's All-Time team) and a Defender of the Year prize in his 12 league seasons. He also played a big part in three MLS Cup triumphs, which included his golden-goal winner in the league’s first-ever title match.
No. 1: Chad Marshall
Every center back that appears in Major League Soccer from here on out will be chasing down the standard set by Marshall. He tops all defenders in league history in career appearances (409), starts (404), shutout participations (116) and Defender of the Year wins (three). He was smart and well-positioned, could run with attackers on the ground or dominate them in the air, and moved the ball expertly out of the back.
After 15 seasons, his trophy case is stuffed with four Best XI citations, two MLS Cups, four Shields and an Open Cup. It will be a good while before anyone matches his extended level of excellence.