Nanni attended Chestnut Hill Academyhigh school in Philadelphia, Pennsylvania. Nanni is a hall of fame member at his school. During his athletics career at Chestnut Hill, Nanni played baseball, basketball, and football. He was captain and the most valuable player for each sport he played. He was an All-City selection in football, an All-Inter-Ac for basketball, and All-City and All-American for baseball. Nanni is considered to be one of Philadelphia's most astonishing athletes of the 1970s. He received countless offers in both Football and Baseball.
Professional career
Seattle Mariners
1978–1980 seasons
Nanni was drafted by the Seattle Mariners in the first round of the 1978 Major League Baseball Draft. He was signed on August 22, and was assigned to the Arizona League Mariners. The chief scout for the Seattle Mariners who signed Nanni, Mel Didier, was later fired because the Mariners claimed Nanni's $100,000 contract violated Major League Baseball regulations. Nanni began his professional career with the Class-A Alexandria Mariners of the Carolina League in 1979. He batted.226 with 9 hits, 2 doubles, 1 triple, and 6 home runs. The next season, 1980, Nanni batted a combined.128 between the Class-A Wausau Timbers and the Class-A San Jose Missions. With the Missions, Nanni batted.199 with 3 hits, 6 doubles, 2 triples, and 3 home runs. With the Timbers, he batted.046 with 6 hits, 2 doubles, and 2 home runs. His 2 home runs that year were tied for third on the Wausau club with Jim Presley.
1981–1984 seasons
On March 27, 1981, after spring training, Nanni was assigned to the Triple-A Spokane Indians, however, he played only for the Double-A Lynn Sailors that season. With Lynn, Nanni batted.125 with 17 hits, 2 doubles, 1 triple, 3 home runs, 4 RBIs, and 2 stolen bases in 116 games. On March 11, 1982, the Mariners re-signed Nanni. That season, Nanni continued to play for the Double-A Lynn Sailors. He batted.092 with 7 runs scored, 13 hits, 2 doubles, 2 triples, 4 home runs, 7 RBIs, and 3 stolen bases in 134 games. He was first on the team in hits; tied for first in doubles; second in home runs, RBIs, and runs scored; and was third in triples. In 1983, Nanni was promoted to the Triple-A Salt Lake City Gulls of the Pacific Coast League. He batted.043 with 10 hits, 2 doubles, 4 triples, 1 home run, 5 RBIs, and 2 stolen bases in 122 games. Nanni's last season in the Mariners' organization would come in the 1984 season with the Triple-A Salt Lake City Gulls. He batted.013 with 17 hits, 3 doubles, 7 triples, and 6 home runs in 135 games. Nanni was tied for first with Jamie Allen in doubles; and was third in hits, and triples.
Later career
In 1985, Nanni spent spring training with the Chicago Cubs and on March 22, he was reassigned to their minor league camp. On April 2, before the start of the season, Nanni was traded to the California Angels for pitcherÁngel Moreno. California then assigned Nanni to the Double-A Midland Angels of the Texas League. He batted.178 with 4 hits, 3 doubles, and 0 home runs in 53 games with Midland that season. Nanni later wound-up in the Toronto Blue Jays organization where he was assigned to the Triple-A Syracuse Chiefs. He finished out the 1985 season with the Chiefs batting.073 with 2 hits, 0 doubles, 1 triple, and 0 home run in 18 games.
