The Green Monster is famous for preventing home runs on many line drives that would clear the walls of other ballparks. A side effect of this is to increase the prevalence of doubles, since this is the most common result when the ball is hit off the wall (often referred to as a “wallball double”). Some left fielders, predominantly those with vast Fenway experience, have become adept at fielding caroms off the wall to throw runners out at second base or hold the batter to a single.
Compared with other current major league parks, the wall’s placement creates a comparatively shallow left field; the wall falls approximately 304–310 feet (93–94 m) from the plate along the left-field foul line. With this short distance, many deep fly balls that could be caught by the fielder in a deeper park rebound off the wall for base hits. And while the wall turns many would-be line-drive homers into doubles it also allows some high yet shallow fly balls to clear the field of play for a home run.