Earl Morrall, arguably the greatest back-up quarterback in NFL history, died on Friday, the Miami Dolphins said. He was 79.

Morrall came off the bench to start the final nine regular-season games of the Dolphins’ 1972 perfect season after starting quarterback Bob Griese was injured. Griese returned in the playoffs and led Miami to a Super Bowl victory. It remains the NFL’s only unbeaten season in history.

Morrall tallied 11 touchdowns and had seven interceptions that season before being named the NFL’s comeback player of the year. He retired in 1977 with three Super Bowl rings.

“Earl not only left an indelible mark in Dolphins history with his play on the field during the perfect season Super Bowl VII championship team, but was extremely active in the community,” Dolphins’ owner Stephen Ross said.

The San Francisco 49ers made Morrall a first-round pick in the 1956 draft. He went on to play 21 seasons with the Dolphins and 49ers and four other teams including Pittsburgh and Detroit.

Morrall also won the 1970 season Super Bowl, where he replaced injured star quarterback Johnny Unitas. Two years earlier, Morrall led Baltimore to a 13-1 record and NFL title, but wound up losing the 1968 season Super Bowl to the New York Jets.

In 255 games, Morrall completed 1379 passes for 20,809 yards and 161 touchdowns with 148 interceptions.