The benchmark of 18 strikeouts is used since it represents about 2/3 of a nine-inning game's 27 outs produced by a single pitcher via a strikeout ("approximately" due to the fact that a pitcher can record more than three strikeouts in an inning with the uncaught third strike rule). The number 18 comes from the conclusion that if a pitcher records one strikeout per inning he will record about six innings worth of work. Multiply that by the number of pitches he throws in an average game (about 250) and you get 18 strikeouts. This mark was first established in 1908 by John McGraw of the New York Giants. Before then, there was no such thing as an official batter's box; rather, there were simply lines on the field where a player would stand while the ball was in play. These lines changed frequently, so much so that many games had no clear area where a batter could be said to have the plate. As a result, some people argued that you could only credit a player with a hit when you saw him run to first base. Others claimed you could also award bases if a player just stood there looking at a pitch. In 1908, however, John McGraw came up with the idea that if a pitcher struck out every hitter he would finish his game. This way, both the pitcher and the team would know how many runs they scored during the game.