by Al Stump, Algonquin Books of Chapel Hill, 464 pages, $24.95. CODE: ALG-1 When Al Stump interviewed a dying Ty Cobb in 1960 and 1961, he got more than he had bargained for. Baseball’s greatest hitter gave the sportswriter a mass of material that could never be used in the autobiography Stump had agreed to ghostwrite. Cobb, it turned out, was not merely mean but psychotically vicious from the very beginning of his professional career, and throughout this new and thorough biography the Georgia Peach does two things with monotonous regularity: lead the league in batting average and beat teammates, opponents, and sometimes total strangers to a pulp. There’s a horrible fascination in learning how Cobb alienated his family and an ever-dwindling circle of friends even as he piled up records and dollars (he played the stock market as shrewdly as he did baseball).