Translation:In soccer, one kicks the ball, not the people.
Changing from active to passive when translating is the kind of things you do when the passive voice is more prevalent in the destination language (as in English, if I'm not mistaken). Not doing so just to stick to the origin sentence structure is a bad (at best poor) translation.
For example, translating "to be ...ing" into "esti ...anta" often makes poor translations.
I'd say that it's because "futbalistojn" is more specific than "homojn;" the English sentence is "In soccer, one kicks the ball, not the people." If you used "futbalistojn" instead of "homojn" then the sentence would be "In soccer, one kicks the ball, not the football players."