whose position was taken by the former DH is replaced by the pitcher, who assumes that player's position in the hitting lineup. The use of the designated hitter, which reduces the need for complicated strategy such as the double-switch, is opposed by many baseball traditionalists. Nevertheless, it is used today at most levels of baseball in the United States and abroad. Major League Baseball's National League was the most prominent league that required pitchers to bat, until allowing the designated hitter beginning with the 2022 season. Rosters The number of players on a major league roster is dictated by the labor agreements worked out between players and management. According to prior rules, a team may have a maximum of 25 men on a roster from Opening Day until August 31. Beginning in the 2012 season, a major league team was allowed to carry a 26th man on its roster when playing the second game of a double-header that was scheduled at least 48 hours in advance. As of 2020, the number has been increased to 26, of whom no more than 14 may be pitchers, with 27 for a doubleheader. After August 31, during the regular season teams may call up additional personnel to the active roster, up to a maximum of 40 players. This number is seldom actually approached, however, with most teams' September rosters peaking at around 30 players. In 2020 the number was limited to 28. In the postseason, rosters are fixed at 25 men. Until 2007, teams could not replace players on their playoff rosters in the event of an injury and had to play out the series shorthanded. Starting in 2007, an injured player could be placed on the disabled list and replaced by another player who was not included on the initial 25-man roster, but the injured player becomes available for the next round of the playoffs should his team advance. Pace of play Rule changes have been implemented at different levels of baseball to quicken the pace of play. In college baseball, the Southeastern Conference experimented with a 20-second pitch clock during the 2010 season, and the NCAA instituted the pitch clock before the 2011 season for when no runners are on base. The pitch clock began to be used in professional baseball as well, first in the Arizona Fall League in 2014 and in the Double-A and Triple-A levels of Minor League