The most successful Yankee ever born on the Fourth also happens to be the oldest of the group. Well, if he was still alive. Jack Warhop, born 1884, debuted with the team in 1908, when they were known as the Highlanders. He spent his entire career with the Yankees, totaling eight years, 221 games, and 1412.2 innings. He finished his career with a 69-92 record, with a 3.12 ERA, 97 ERA+, 18.0 rWAR. He had some very good seasons (6.5 rWAR in 1912, 4.6 in1909, and 3.8 in 1914), but he lacked consistency. Those were the only three years he had ERA+ above league-average, and he produced 82.8% of his career rWAR in those three seasons. He is also remembered as the pitcher who Babe Ruth took deep for the first two home runs of his career.
Hal Lanier spent 10 years in the big leagues, debuting with the San Francisco Giants in 1964. He was a terrible offensive middle infielder during the height of the second dead ball era, posting a career OPS+ of 50. However, he was a strong defender, which allowed him to be a starter in the majors for the first seven years of his career. At age 29, he joined the Yankees as a utility infielder. He spent 1972 and 1973 wearing the pinstripes, playing 95 games and collecting 197 plate appearances, posting a horrendous 43 OPS+ and -0.5 rWAR. He was the son of Max Lanier, an unknown but successful pitcher of the 1940s, with a career 30.1 rWAR. Hal later spent three years (1986-1988) managing the Astros, putting up a respectable 254-232 record (.523 Winning %). Surprisingly, he hasn't managed in the big leagues since.
Jim Beattie was drafted by the Yankees in the fourth round of the 1975 amateur draft out of Dartmouth College. He made his major league debut with the team in 1978 and played with the team through the 1979 season. Over his two seasons with the team, he had a 9-15 record, with a 4.28 ERA, 89 ERA+, 0.9 rWAR. In November 1979, he was traded to the Seattle Mariners, where he spent the remainder of his career. His last season was 1986 as a 31-year-old, finishing with a 52-87 record, and a 4.17 ERA, 98 ERA+, 15.2 rWAR. He was especially effective from 1982 to 1984, producing 13.4 rWAR, 88.2% of his career value. Beattie has stayed in the game since he retired as a player, serving as general manger of the Montreal Expos (1995-2001) and Baltimore Orioles (2003-2005), as well as a scout with the Toronto Blue Jays since 2010.
The most recent Yankee player born on July Fourth was Amauri Sanit, who debuted with the Yankees in 2011, pitched seven terrible innings, and hasn't been heard from since. Over those seven innings, he put up a 12.86 ERA, 35 ERA+ and -0.3 rWAR. The Cuban defector was signed by the Yankees and made his professional debut in the minors in 2008. He was okay as a reliever in 2009, but terrible in 2010 and 2011. I remember being confused when they decided to bring him up to the team and he did nothing to quell that confusion. He was released by the team after the 2011 season and has spent the past two years playing in Mexico. He's actually turned into a surprisingly solid starter down there in 2013, so maybe he will make a return to the big leagues one day.
So there you have it - the four players who have donned the pinstripes and were born on the Fourth of July. Happy Independence Day everyone, and happy birthday to Misters Warhop, Lanier, Beattie, and Sanit!