The previous thoughts were quite accurate. Money is the fundamental difference between sports in a pre- modern and modern sense. Sports has evolved into a business that involves more than just the athlete and a particular organization. Agents, handlers, publicists, web designers, marketing gurus, trainers, advisers, and others have become directly connected to the sports industry. It has become a realm where the role of money and influence has almost superseded the sport, itself. The idea of corporate sponsorship and paying heed to the force of money has become so dominant that the activity is almost an afterthought. The appeal of sports is so global and involves so many interests that this is almost inevitable, to a certain extent. One cannot ignore this difference between pre modern and modern sports.
"...sports as we know them are something new under the sun." Our sports are different from those of ancient, folk, or medieval cultures. "Specifically, these differences lie in the growth of bureaucracies, the focus on records and quantifiable performance, increased specialization of roles, increased equality in and for competition, and the move to standardize rules and techniques." The most important aspect of both college and professional sports may be the counting of the money; they are multi-million dollar businesses; they are not played at but worked at and not by recreationists but by professionals.
Stephen Hardey, "Entrepreneurs, Structures, and Sportgeist: Old Tensions in a Modern Industry," in Donald G. Klye and G. D. Stark, eds., Essays on Sport History and Sport Mythology (College Station: Texas A & M University Press, 1990), 45-82.
John W. Loy and others, Sports and Social Systems: A Guide to the Analysis, Problems, and Literature (Addison-Wesley, 1978), 256, 257, 258, & 263-279.
In the early days of professional sports, you could forget about massive contracts and signing bonuses. Babe Ruth, in his heyday, getting a contract for $30,000 a year was a huge and unprecedented sum. The leagues were smaller and the teams farther apart in all sports. Teams played regionally instead of nationally and in many sports, there was no such thing as a real playoff system or championship. Football players had leather helmets and no pads, pitchers always pitched complete games because relief pitchers did not yet exist, and basketball teams as well as all others were exclusively white.
Until the advent of radio, these sports were not nearly as popular either, with baseball and boxing really becoming national sports once everyone could listen to them for free in whatever city they were in.