It was because of these ritual practices around the game that it was deemed “demonic” by the invading/occupying Spaniards and outlawed.
Well, there were other ritual practises they might have banned it for as well (killjoys!). From Teh Wiki.…
The association between human sacrifice and the ballgame appears rather late in the archaeological record, no earlier than the Classic era.[61][62] The association was particularly strong within the Classic Veracruz and the Maya cultures, where the most explicit depictions of human sacrifice can be seen on the ballcourt panels—for example at El Tajín (850–1100 CE)[63] and at Chichen Itza (900–1200 CE)—as well as on the decapitated ballplayer stelae from the Classic Veracruz site of Aparicio (700–900 CE). The Postclassic Maya religious and quasi-historical narrative, the Popol Vuh, also links human sacrifice with the ballgame (see below).
Captives were often shown in Maya art, and it is assumed that these captives were sacrificed after losing a rigged ritual ballgame.[64] Rather than nearly nude and sometimes battered captives, however, the ballcourts at El Tajín and Chichen Itza show the sacrifice of practiced ballplayers, perhaps the captain of a team.[65][66] Decapitation is particularly associated with the ballgame—severed heads are featured in much Late Classic ballgame art and appear repeatedly in the Popol Vuh. There has been speculation that the heads and skulls were used as balls.[67]
