The above expression illustrates a verb executed on a subject and object which are two distinct entities. This is your Forth example (which I agreed with earlier).

In the dot syntax though, you use it as an indicator of possessiveness, in which case the subject is reduced to "ball", modified by "boy". Furthermore "is kicked" is a passive form, which means it has an implied subject, which is the boy. Therefore the completed expression cannot be written as-is; you'd have to insert the subject (boy) into the expression and delineate it as a separate entity.

boy.kick(boy.ball) would convey this meaning. boy.ball.kicked() could also convey it, but in this case, the innards of kicked() must make reference to boy.