NEW YORK--Relief ace Willie Hernandez of the world champion Detroit Tigers was named the Most Valuable Player in the American League yesterday.

Hernandez, who saved 32 games in 33 opportunities and posted a 9-3 record with a 1.92 earned run average also won the AL Cy Young Award last week.

He thus became the fourth American League pitcher to win both awards. Rollie Fingers of Milwaukee did it in 1981, Oakland's Vida Blue won both in 1971, and Denny McLain of Detroit, the last Tiger MVP, swept the awards in 1968.

Three National League pitchers--Bob Gibson of St. Louis in 1968, Sandy Koufax of Los Angeles in 1963 and Don Newcombe of the Brooklyn Dodgers in 1956--scored Cy Young and MVP sweeps.

Hernandez received 16 of the 28 first-place votes and totaled 306 points in outdistancing Minnesotn first baseman Kent Hrbek, who had five first-place votes and 247 points. Hrbek batted .311 with 27 home runs and 107 runs batted in, leading the Twins into surprising pennant contention last season.

Dan Quisenberry, bullpen star for the Kansas City Royal, finished third with five first-place votes and 235 points. Quisenberry had a 6-3 record and 44 saves, one short of his major league record.

Baltimore first baseman Eddie Murray finished fourth in the balloting, receiving the other two first-place votes and 197 points.

Don Mattingly of the New York Yankees, the AL batting champion, finished fifth with 113 points, followed by Detroit's Kirk Gibson with 96, Tony Armas of Boston with 87' and the Yankees' Dave Winfield with 83.

Detroit's Alan Trammell, the World Series MVP, was ninth with 76' and Willie Wilson of Kansas City had 61, completing the top 10.

Baltimore's Cal Riphan Jr., last year's AL MVP with 322 points, received just one 10th place vote for a single point in this year's election.