In March 1915, Ruth reported to [[Hot Springs, Arkansas]], for his first major league [[spring training]]. Despite a relatively successful first season, he was not slated to start regularly for the Red Sox, who already had two "superb" left-handed pitchers, according to Creamer: the established stars [[Dutch Leonard (left-handed pitcher)|Dutch Leonard]], who had broken the record for the lowest [[earned run average]] (ERA) in a single season; and [[Ray Collins (baseball)|Ray Collins]], a 20-game winner in both 1913 and 1914.{{sfnp|Creamer|1992|p=104}} Ruth was ineffective in his first start, taking the loss in the third game of the season. Injuries and ineffective pitching by other Boston pitchers gave Ruth another chance, and after some good [[relief pitcher|relief]] appearances, Carrigan allowed Ruth another start, and he won a rain-shortened seven inning game. Ten days later, the manager had him start against the New York Yankees at the [[Polo Grounds]]. Ruth took a 3–2 lead into the ninth, but lost the game 4–3 in 13 innings. Ruth, hitting ninth as was customary for pitchers, hit a massive home run into the upper deck in [[right fielder|right field]] off of [[Jack Warhop]]. At the time, home runs were rare in baseball, and Ruth's majestic shot awed the crowd. The winning pitcher, Warhop, would in August 1915 conclude a major league career of eight seasons, undistinguished but for being the first major league pitcher to give up a home run to Babe Ruth.<ref>{{harvp|Creamer|1992|p=106}}</ref>
[[File:Babe Ruth by Conlon, 1916.jpeg|thumb|left|Ruth during batting practice with the [[Boston Red Sox]] in 1916.]]
Carrigan was sufficiently impressed by Ruth's pitching to give him a spot in the starting rotation. Ruth finished the 1915 season 18–8 as a pitcher; as a hitter, he batted .315 and had four home runs. The Red Sox won the [[List of American League pennant winners|AL pennant]], but with the pitching staff healthy, Ruth was not called upon to pitch in the [[1915 World Series]] against the [[Philadelphia Phillies]]. Boston won in five games;. Ruth was used as a pinch hitter in Game Five, but [[Ground out (baseball)|grounded out]] against Phillies ace [[Grover Cleveland Alexander]].<ref>{{harvp|Montville|2006|pp=50–52}}</ref> Despite his success as a pitcher, Ruth was acquiring a reputation for long home runs; at [[Sportsman's Park]] against the [[St. Louis Browns]], a Ruth hit soared over Grand Avenue, breaking the window of a [[Chevrolet]] dealership.<ref>{{harvp|Wagenheim|1974|pp=33}}</ref>
In 1916, there was attention focused on Ruth for his's pitching, as he engaged in repeated pitching duels with the ace of the Washington Senators,' ace [[Walter Johnson]]. The two met five times during the season, with Ruth winning four and Johnson one (Ruth had a [[Win–loss record (pitching)|no decision]] in Johnson's victory). Two of Ruth's victories were by the score of 1–0, one in a 13-inning game. Of the 1–0 [[Shutouts in baseball|shutout]] decided without extra innings, ALAmerican League Presidentpresident [[Ban Johnson]] stated, "That was one of the best ball games I have ever seen."<ref>{{harvp|Montville|2006|pp=56–57}}</ref> For the season, Ruth went 23–12, with a 1.75 ERA and nine shutouts, both of which led the league.<ref>{{harvp|Montville|2006|pp=55}}</ref> Ruth's nine shutouts in 1916 set a league record for left-handers that would remain unmatched until [[Ron Guidry]] tied it in 1978.<ref>{{cite web|last=Schlueter|first=Roger|title=Verlander's 2011 was epic|work=MLB.com|url=http://mlb.mlb.com/news/print.jsp?ymd=20120223&content_id=26813526&vkey=news_mlb&c_id=mlb|access-date=January 20, 2014|archive-url=https://web.archive.org/web/20160304040445/http://mlb.mlb.com/news/print.jsp?ymd=20120223&content_id=26813526&vkey=news_mlb&c_id=mlb|archive-date=March 4, 2016|url-status=live}}</ref> The Red Sox won the pennant and [[1916 World Series|World Series]] again, this time defeating the [[Brooklyn Dodgers|Brooklyn Robins]] (as the Dodgers were then known) in five games. Ruth started and won Game 2, 2–1, in 14 innings. Until another game of that length was played in [[2005 World Series|2005]], this was the longest World Series game,{{efn|An 18 inning World Series game, also between the Red Sox and Dodgers, was played in 2018.}} and Ruth's pitching performance is still the longest postseason [[complete game]] victory.<ref name="99facts">{{cite web|last=Corcoran|first=Cliff|url=http://mlb.si.com/2013/07/11/99-cool-facts-about-babe-ruth/|date=July 11, 2013|access-date=January 20, 2014|title=99 cool facts about Babe Ruth|work=[[Sports Illustrated]]|url-status=dead|archive-url=https://web.archive.org/web/20140208062047/http://mlb.si.com/2013/07/11/99-cool-facts-about-babe-ruth/|archive-date=February 8, 2014}}</ref><ref>{{cite news|last=Berg|first=Ted|url=http://ftw.usatoday.com/2013/10/12-longest-games-in-mlb-postseason-history/|access-date=January 20, 2014|title=12 longest games in MLB postseason history|work=[[USA Today]]|archive-url=https://web.archive.org/web/20140202121315/http://ftw.usatoday.com/2013/10/12-longest-games-in-mlb-postseason-history/|archive-date=February 2, 2014|url-status=live}}</ref><ref>{{harvp|Wagenheim|1974|p=38}}</ref>
Carrigan retired as player and manager after 1916, returning to his native Maine to be a businessman. Ruth, who played under four managers who are in the [[National Baseball Hall of Fame and Museum|National Baseball Hall of Fame]], always maintained that Carrigan, who is not enshrined there, was the best skipper he ever played for.<ref>{{harvp|Creamer|1992|pp=33, 85}}</ref> There were other changes in the Red Sox organization that offseason, as Lannin sold the team to a three-man group headed by New York theatrical promoter [[Harry Frazee]].<ref>{{harvp|Creamer|1992|p=133}}</ref> [[Jack Barry (baseball)|Jack Barry]] was hired by Frazee as manager.<ref>{{harvp|Creamer|1992|p=134}}</ref>
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