Saccharin would be a more accurate title for this smug, premature memoir from Walter Payton, who in a three-year career with the Chicago Bears has become one of professonal football's top running backs has rung up a host of records. Here he comes across as a sort of evangelical Pollyanna bent on claiming full credit for the Lord of the Southern Baptists and his superstar son. Teammates, he confides, nicknamed him Sweetness for his unselfishness on and off the playing field. Perhaps. But Payton neglects to make clear just what his brand of muscular Christianity has to do with pigskin prowess, much less the game of life. Since the manchild author has yet to turn 25, he must pad his story of a comfortable, happy childhood in rural Mississippi, followed by four productive years at Jackson State University, with statistical accounts of every high-school and college game he played in. His comparatively brief span with the Second City's luckless eleven also is treated summarily, with virtually no hint of the personal price of victory or the cost of defeat. At a minimum, it's hard to accept the bland assertion that a visible, successful young black like the author has encountered no racial discrimination anywhere along the line. The brash impieties of Joe Namath, Jerry Kramer, Joe Schmidt, et al. seem models of literary attainment in comparison with such bosh.