Both Stela 4 and Stela F portray Waxaklahun-Ubah-K'awil [18-Rabbit] as a ballplayer.
"The principal altar for Stela 4 depicts a flattened sphere bound by a twisted cord. Similar objects appear on the markers from Ballcourt IIb, where we can identify them as rubber balls still hanging from a binding rope tied to the rafters of a house. The Maya apparently stored their rubber balls in this way to keep them round."
Linda Schele & Peter Mathews, The Code of Kings: The Language of Seven Sacred Maya Temples and Tombs, p. 152