Acosta had been with the Yankees as manager of the organization's Gulf Coast League rookie team, and as an instructor. A former minor league pitcher with the Philadelphia Phillies, he went on to manage the Class-A Lansing Lugnuts of the Midwest League in 1999 when the team still maintained affiliation with the Cubs.
The following year, Acosta became the Cubs' third pitching coach in as many seasons, succeeding Marty DeMerritt.
He resigned in 2001 following a well-publicized rift with manager Don Baylor. At the time, it was clear that the majority of Cub pitchers were in Acosta's corner and it was widely speculated that this contributed in some part to Baylor's demise the following year when he was fired in July 2002.
Acosta later became the Texas Rangers pitching coach in 2002, but was fired just two months into the season by manager Jerry Narron. While he was with the Cubs, Acosta helped spearhead a major turnaround from the team's beleaguered 2000 pitching staff into that of his commendable 2001 posse.
In 2000, the Cubs had posted a 5.25 ERA with their best starter -- Jon Lieber -- finishing with a 4.41 average. But the Cubs' 4.03 staff ERA in 2001 was a true testament to Acosta's work. His staff ranked fourth in the National League in ERA as the Cubs won 88 games that year.
Acosta also helped produce the Cubs' first 20-game winner in Lieber since Greg Maddux in 1992. The very day Lieber earned his 20th win on Oct. 3, Acosta resigned.
He was succeeded by Larry Rothschild, now in his fifth season as Cubs pitching coach. This would have been Acosta's third season managing the Yankees Gulf Coast League affiliate.
Oscar Acosta is survived by his wife, Kathy, and three children: Melissa, Amanda, and Ryan.