Boswell on baseball: a super team; How Life Imitates the World Series, by Thomas Boswell. New York: Doubleday & Co. 296 pp. $14.95.

''You are part of an entertainment,'' Sandy Koufax, the most remarkable pitcher of the past 25 years, has said of his sport. Part of a show indeed. ''But,'' he continues, ''you are not an entertainer.'' Recognizing the presence of these seemingly contradictory components, tracing the human complexity of our most venerable game, are the distinguishing features of a growing number of remarkable commentators on baseball.

Bill James, Pat Jordan, and Roger Angell are three such observers, and to their select committee needs now to be proposed the candidacy of Thomas Boswell. Boswell writes about baseball regularly for the Washington Post and occasionally for Inside Sports. His talent and accomplishments are noteworthy, and, while he is not yet at the rarefied level of the fellows cited above, he may reach it, and, certainly, following his progress is going to be interesting itself.

His first collection, ''How Life Imitates the World Series,'' treats an appropriately broad range of aspects of the national pastime. These include life in the minor leagues for an aristocratic suburbanite, Cuban and Puerto Rican ''beisbol,'' the extraordinary tension in this pastoral sport, a new, fascinating method of computing offensive statistics, and a glimpse of Boswell's own street youth. It also covers some recent games and series in detail, among them the 1978 Red Sox-Yankee playoff game (''The Greatest Game Ever Played,'' according to Boswell), and the '79 and '80 World Series. It features individuals as well, including Pete Rose, Rod Carew, Steve Carlton, Bill Veeck, George Brett , and, Earl Weaver.

Although the nation's capital has not been able to support a baseball team for the past decade, Boswell has adopted the Baltimore Orioles his home team. The ''Birds'' have been, arguably, the most interesting team in the game for a couple of decades, so as a result of his home base and his travels, Boswell has had a fertile range of baseball topics and personalities available to him.

He has, in sporting parlance, been given his chance -- and for the most part has used it well. Modestly, he reports that ''. . . the opinions that appear under my name, no matter how subjective they sound, are almost never my own. They are an amalgam, a blending and counterpointing. . . .'' He is expert at this melding, and he has allowed others to speak wonderfully. Quoting one of the sanctified wizards of the game, batting coach Charlie Lau, he writes: ''The player who ages poorly is the one who lets his vanity get in the way of his judgment.'' Pursuing the elusive, silent Steve Carlton, Boswell learns from Tim McCarver (the pitcher's personal catcher for many years) that Carlton always tries to eliminate every consideration from pitching except pitching itself. ''He's playing,'' McCarver elucidates, ''an elevated game of catch.''

But Boswell has his views, too. ''This was baseball at its wealthiest,'' he reports of a crucial play in the 1980 American League Championship Playoffs, ''with the eyes darting a dozen times on one play, measuring time and distance, guessing at the limits of luck and skill. . . .'' Of his own first baseball glove, he acknowledges it was ''. . . the last toy and the first personal possession.''

He is firmly conscious of baseball's ordinary, daily life and of the ways these mundane, lived details fan out into mystical and mythical dimensions. He writes well generally but especially so in his longer pieces. He has fine perceptions about the game, for the most part, but occasionally treats his subjects too quickly; his book would be better if he had not been confined to writing primarily about the game's recent past. He is a serious candidate for entry into the best circles of baseball commentary, but he's not quite admissible yet. Baseball is an entertainment filled with performers who are touched by, and touch in us, something deeper and stronger than mere pleasure. Thomas Boswell has given his readers access to those depths and will, no doubt, give them greater access in the future.