The guys are playing a sport.
guys play in a park
Sports are played in areas other than parks.  Even if it looks like a park, it could be on private property, such as a wealthy person's lawn.
exists e1 x1 x2.(n_guy(x1) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_sport(x2))
exists e1 x1 x2.(in(e1,x2) & n_park(x2) & Actor(e1,x1) & v_play(e1) & n_guy(x1))