It is not easy being me,"" baseball's supersensitive slugger has been heard to say--so it's no surprise that this solidly researched, sympathetic bio is revealing without being wholly enlightening. Between Reggie's auspicious start (on the gridiron, too, at Arizona State) through last season's playoff let-down, we see the complex, articulate Jackson acquire a reputation as a home-run hitter able to produce under pressure--and as a league-leading braggart. . . who just may be more convinced than conceited. One way or other, emotional security seems to have eluded him. As Allen sees it, Jackson's noisy run-ins--with owners, managers (notably, Billy Martin), and other players--stem from a deep-seated desire for affection and attention, as well as respect. This penchant for psycho-dramatics may be attributable, in turn, to an early rejection: when Mom split to Baltimore from Wyncote, Pa., she took only three of the six kids, leaving Reggie behind with Dad. Racial slights, real and imagined, also seem to be involved. The verdict of his teammates? Indecisive but intriguing. ""I go back to 1965 with Reggie,"" says Rick Monday, now a Dodger outfielder. ""But I guess I don't go far enough back to remember when he was shy."" Or, fellow-Yankee Luis Tiant: ""Sure, he's a lotta bullshit, but we all a lotta bullshit sometime."" Indicative of Jackson's elusive yet pervasive image is a vignette contributed (thanks to Allen's patient digging) by ex-wife Juanita (Jennie) Campos, a specialist in Asian studies: she bemusedly recalls picking up a copy of Time with Jackson's picture on the cover--in Nepal. Maury Allen's second hit of the season (see also Baseball's 100, above), and some of the answers that Reggie Jackson's fans have been waiting for.