As a young corporation lawyer "Sam" Aldrich caught the eye of New York's forthright Police Commissioner Stephen P. Kennedy. Today Aldrich, a son of Winthrop Aldrich, former U.S. Ambassador to Britain, heads the Police Athletic League, appropriately abbreviated to PAL, the largest privately financed youth program in the city. In 40 centers, most of them in neighborhoods where no other recreational opportunities exist, PAL each year keeps some 100,000 boys and girls off the street and on baseball diamonds, basketball courts and in boxing rings. For 13 consecutive years PAL boxers have taken the Metropolitan AAU Championships. Among PAL alumni are such nationally rated fighters as Sugar Ray Robinson and Ralph (Tiger) Jones. The other day 28 young fighters climbed into the ring at St. Nicholas Arena. Both Angel Morales (left, with Aldrich), PAL's outstanding fighter this year, and Vincent Gentile won PAL championships. But, as Aldrich says: "What counts is not only what they accomplish here, but what could happen to them if PAL did not exist."