A synonym for 'basketball player' is 'cager'. What is the origin of that meaning?

?In its early days, basketball was not a sport for the faint of heart. Fights were commonplace, fans lobbed produce onto the court, and sometimes, much like in baseball, kept the Spalding as a souvenir when it bounded into the crowd. In those days, when the rules still stated that the player who got to an out-of-bounds ball first would retain possession, the ensuing result was lots of diving into the spectators and other slowdowns in play.

Hence, a solution was necessary. Enter: a cage.

The first instance of a caged basketball game occurred in Trenton, N.J. in 1896, In the following decades, cages would become ubiquitous, and the term "cagers" synonymous with basketball players. The rough-and-tumble era of cagers, in which professionals often returned home to their wives and girlfriends with serious rope burns, endeared basketball in the hearts and minds of many Americans.