A local hero in Warren, Ohio, Hal signed with the Yankees shortly after graduating from Chaffey High School in 1956. He struggled until his fourth year in organized baseball, when he won 21 games for Modesto with a 3.19 ERA. He would not reach those heights again, but after two more reasonably strong years in the minors, he made it to New York in June 1961. He would be used exclusively in the bullpen as a big leaguer. Although Reniff struggled with his control (31 walks in 45 and 1/3 innings), he fooled enough batters to post a 2.58 ERA. He was not used in the Yanks' World Series win over the Reds.
After missing most of 1962, his true sophomore effort was a good one. Reniff led the 1963 Yankees with 18 saves, while pitching to a 2.62 ERA. While the Yankees were swept by the Dodgers in the World Series, the righthander was impressive, allowing just one walk in three scoreless innings. Another strong year (6-4, 9 SV, 3.12 ERA) finished with another World Series loss in 1964. Hal saw just one-third of an inning of work against the Cardinals, allowing two hits before Pete Mikkelsen bailed him out.
Hal spent only three more seasons in New York, even though his earned run average never exceeded 3.80. In 1967, his final year in the bigs, he was acquired by the Mets in midseason. But the Yankees, having reacquired the portly pitcher in the offseason, kept him at AAA Syracuse from 1968 through 1972, when he finally called it quits at age 34.
According to the B-R Bullpen, Hal Reniff dabbled in acting post-baseball. The Internet Movie Database has a few listings for a Hal Reniff, and I can't imagine it's a very common name. He passed away in Ontario, California in 2004 at age 66.
Fun fact: Hal's first major league win came on August 6, 1961. The Twins and Yankees were tied at six in the 13th inning when he got the call from the dugout. He pitched three scoreless innings before Yogi Berra scored Bobby Richardson with a groundout in the bottom of the 15th.