This spring, when it was discovered that as a result of last season's beaning Tony Conigliaro could no longer see well enough to hit, the Red Sox began an unhappy search to find a replacement for their fine young outfielder. After experimenting with other players early in the year, Sox Manager Dick Williams found he should have looked no farther than his bench, where Ken Harrelson, a utility man who had an unimpressive World Series, was still sitting. The 26-year-old former Athletic, whose only notable achievement in the big leagues was to gain a reputation as the best golfer in baseball, stepped into Tony C.'s spot in late April and quickly proved he was the hitter the Red Sox needed to back up Carl Yastrzemski. Harrelson's batting, which includes team leadership in home runs (14) and RBIs (40) and Boston's second best average (.297), disputes his claim that "Tony's shoes are big ones, and I still can't fill them." By his own admission Harrelson started becoming the kind of hitter who could step in for Conigliaro last year in Kansas City under Manager Alvin Dark. "I owe everything I am now to Dark," says Harrelson. "He's the one who really got me started as a hitter by teaching me to stroke the ball around and not consciously go for the homer. Without his help, I might have quit baseball to become a pro golfer." Dark, who now manages the Indians, was wishing last Friday that his former student had been just a little less attentive. Using Dark's technique of concentration and a controlled swing, Harrelson belted three straight homers and drove across all seven runs in one Boston win over the Indians and hit a game-deciding three-run shot in another.