The average NFL CB is the same size as a striker, but quicker and faster. And it isn't even all that close. Its the living and breathing soccer that matters. In those places, the best athletes play soccer. In the US, they play football or basketball. And if you think you can do anything at a pro level without extreme levels of athleticism, you are greatly deluded.

The amount of distance covered in a soccer game is twice that of a cornerback in an NFL game. Unlike NFL, soccer also has very limited substitutions so you can't readily swap in fresh legs. An athlete needs to be able to go the full distance at a high level.

A natural cornerback isn't going to be "quicker and faster" over that many miles without a different kind of conditioning that probably favors different genetics. That said, I do think the game would translate well for some cornerbacks in some roles.