Carter was selected by the
Chicago Bears in the
sixth round of the
1967 NFL/AFL draft, After complaining about lack of playing time after the
1969 season he was waived by the Bears and briefly joined the
Buffalo Bills. After
Cincinnati Bengals' quarterback
Greg Cook was injured during the
1970 preseason, Carter was traded by the Bills to the Bengals in exchange for a draft choice. He led the NFL in pass completion percentage in
1971 and was third in overall passing. His best game of that season was the opener, in which the Bengals defeated the
Philadelphia Eagles 37–14. Carter completed 22 of 30 attempts for 273 yards, three touchdowns, and no interceptions. In the
following year, he split time with
Ken Anderson before Anderson took sole possession of the starting job. In
1973, the Bengals decided to go with Anderson as the starting quarterback, but Carter had to miss the entire season due to a broken collarbone. In 1974, Carter was traded to the
San Diego Chargers for quarterback
Wayne Clark, but opted to sign with the
Chicago Fire of the new
World Football League. The Chargers attempted to void the trade under the claim that Carter's collarbone had not healed, but the league approved the trade anyway. Carter was the WFL's leading passer in
1974 until an injury sidelined him in week eleven. He finished the season with 358 attempts completing 195 for 2629 yards. He threw 27 touchdown passes and was intercepted 16 times. The Fire offense in 1974 is compared today to the
West Coast offense. In , he went to the
Chargers, then was traded to the
Bears during the season, and retired after the
1976 season. Carter was a highly intelligent quarterback, who blossomed in Cincinnati under the West Coast system implemented by
Bill Walsh, then the Bengals' quarterbacks coach and later head coach of the San Francisco 49ers. In his first stint with the Bears, Carter earned a master's degree from
Northwestern University in
Evanston, and while in Cincinnati with the Bengals taught statistics and mathematics at
Xavier University. == Work in Football Analytics ==