"...it has long been thought that the main religious connotations of the Mesoamerican ballgame were the perpetuation of natural cycles such as the movements of the sun and of other celestial bodies, and of the transition of the seasons and of fertility. At Copán, the vegetation scrolls found on the roof drains of the ballcourt, and the maize vegetation motif repeated 32 time of the façades of the two buildings, clearly refer to the fertility cult. When the king or his representatives defeated the forces of disease, drought, and death -- symbolized in the costumes of the members of the opposing team -- he succeeded in ensuring that the sun would once again continue to rise triumphant in the east and that the rains would be plentiful and arrive on time.
There is abundant evidence from other Classic Maya sites that losers in the ballgame were sacrificed, and it is entirely possible that in his day Ruler 13 himself dispatched a few vanquished players. On one altar, and on a small stone cylinder now on display in the Copán Museum, Ruler 13 also cites the captures made in war against some smaller sites in the region. Indeed, Linda Schele believes that he was in pursuit of captives for the dedication of his new ballcourt when he was himself captured, and subsequently beheaded on 3 May AD 738 by the ruler Cauac Sky from the site of Quiriguá. The question of how this long-lived and distinguished Copán dynast was killed by a rival from a much smaller kingdom has perplexed scholars for some time. "
William L. Fash, Scribes, Warriors and Kings: The City of Copán and the Ancient Maya, p. 126-29