constitutes a regulation game, encouraging schools to play as many nine-inning games as possible. Seven-inning games may be played on the final day of a conference series, or if the two teams in a non-conference match will play two games in one day, often to make up a game that could not be played earlier in the year due to inclement weather. A mercy rule may be in use, which terminates play when one team is ahead by 10 or more runs after seven innings (6½ innings if the home team is winning). In games that are scheduled for seven innings the rule takes effect in the fifth. This rule is not used in NCAA tournament games. Several conferences institute this rule only on Sundays or the final day of a conference series so that the visiting team can travel early. In some conferences, the mercy rule may also be used to end such games in order to start the next tournament game sooner. There is an automatic ejection for maliciously running into a defender who is trying to tag a runner or execute a force out. An automatic double play may also be called if a player slides into a base in an attempt to take out the defensive player who is trying to throw the ball to complete a double play. In televised games and in tournament games, instant replay may be used to determine if a slide was malicious. Metal versus wood bat Though a wood bat is legal in NCAA competition, players overwhelmingly prefer and use a metal bat. The metal bat was implemented in college baseball in 1975. Use of a metal bat is somewhat controversial. Supporters of an aluminum or composite bat note that it can increase offensive performance, as the speed of a ball off a metal bat is generally faster than off a wood bat. Those against metal, and for wood, argue that a metal bat is not safe to use, and that a metal bat doesn't prepare players for the next level, as professional baseball uses a wood bat exclusively. In the 2011 season the NCAA changed the requirements for a metal bat, reducing the maximum allowed exit speed in a way that is said to produce a feeling more like a wood bat. As a result, in 2011 there was a drop-off in overall "long" drives or home runs relative