Jay Mariotti, the opinionated and polarizing sports columnist for the Chicago Sun-Times, has resigned after 17 years with the paper, he told the Tribune on Tuesday night. Just back from Beijing, where he covered the Olympics, Mariotti said in a phone interview that he decided to quit after it became clear while in China that sports journalism had become "entirely a Web site business. There were not many newspapers there." He added that most of the journalists covering the Games were "there writing for Web sites." He said he "is talking with a lot of Web sites" and added that the future of his business "sadly is not in newspapers." "I'm a competitor and I get the sense this marketplace doesn't compete," he said. "Everyone is hanging on for dear life at both papers. I think probably the days of high-stakes competition in Chicago are over. To see what has happened in this business. … I don't want to go down with it."