Complete Games are awarded to a pitcher when they have pitched every inning played and faced every batter in the game without the benefit of a relief pitcher.
More about Complete Games Leaders
Complete games are becoming more and more of a rarity in baseball for a variety of reasons, including increased awareness of pitch counts (and some might say an over awareness of pitch counts), increased use in relievers and in particular specialty relievers, and an increased number of pitches batters see per plate appearance. Currently, pitchers who are able to pitch five or more complete games per year are considered a rarity and are generally recognized as “workhorses”. Twenty or so years ago there were approximately double the number of complete games thrown by league leaders, but unless there is a fundamental shift in how pitchers are utilized in the future the number of complete games thrown will likely continue to go down, or at least remain stagnant.