Murphy was given credit for articulating a trade with the Washington Senators for their manager, Gil Hodges. He traded RHP Bill Denehy to the Senators for the rights to Hodges. The Mets were looking for a manager as Wes Westrum was relieved of his duties during the 1967 season, being replaced on the interim basis by Salty Parker.
He was born in New York City, going to Fordham Prep High School in the Bronx and Fordham University as well. Signed by the New York Yankees at age 19 in 1928, he made his MLB debut as a relief pitcher on the 1932 Yankees, giving up 6 runs in 3 1/3 IP over 2 outings (16.20 ERA). Due to the teams carrying a limited number of players on their team throughout the season, it was considered a given to give each player who appeared in a game for the team a World Series ring. Murphy would pick up the first of his 7 World Series rings he would earn by wearing the Yankees pinstripes.
After not pitching in the majors in the 1933 season, he made his first impact on the 1934 team. He got into 40 games, starting 20 of them. Murphy went 14-10, 3.12 and pitched in 207 innings for the Bombers. The following season, he would find his niche as a late game reliever for the Yankees. Though the stat was unofficial at the time, Murphy led the AL in saves 4 different seasons (1938, 1939, 1941, 1942), while leading the AL in 1941 with 31 games finished. Being part of the WS Championship Yankees in 1932, 1936, 1937, 1938, 1939, 1941 and 1943, he was one of only three Yankees players to be part of all seven of those titles (Bill Dickey, Frankie Crosetti and manager Joe McCarthy were the others).
Murphy served in the US Military during the seasons of 1944 and 1945 before returning to the Yankees in 1946. Before the start of the 1947 season, Murphy was released. He would then sign with the rival Boston Red Sox where he finished his career that season. The Yankees, under new manager Bucky Harris, would win the World Series once again. Only Crosetti would appear for the Yankees that season, playing in 3 games, getting 1 at bat. However, Crosetti was a player coach, earning his 8th WS ring.
After the 1947 season, Murphy moved right into the Red Sox front office. He ran the scouting a farm department of the Red Sox from 1948-1960, when he was let go. Weiss, the former Yankees farm and scouting director, took over as GM of the New York Mets, he brought Murphy with him as an assistant. He remained in the front office through the time Devine left to go back to St Louis. His last sight on a MLB field was the New York Mets celebrating the 1969 World Series title, signifying the 8th time Johnny Murphy could say he was part of a World Series Champion.