John Hadl, who became one of the leading quarterbacks in the old American Football League with the San Diego Chargers and later helped take the Los Angeles Rams to an unexpected N.F.L. playoff berth in a career spanning 16 pro seasons, died on Wednesday. He was 82.

The University of Kansas, where Hadl played quarterback, announced the death. The statement did not say where he died or give the cause of his death.

When the A.F.L. and the N.F.L. held separate 1962 drafts long before the leagues merged, it wasn’t clear whether Hadl was best suited to be a passer or a runner in the pro game.

He had been an outstanding running back as a sophomore at Kansas but played quarterback for his final two seasons in a run-oriented offense, gaining All-America honors as a senior.

The Chargers (now the Los Angeles Chargers) selected Hadl in the third round of the A.F.L. draft, envisioning him as their quarterback of the future. The Detroit Lions chose him in the first round of the National Football League draft (the No. 10 selection over all), planning to use him as a running back who might throw out of pass-run option plays.

“At halfback I might have made it for two, three years, maybe,” Hadl told The San Diego Union-Tribune in 1994, when he was inducted into the College Football Hall of Fame. “At quarterback you can play a long time if you make it, and that’s what happened.”

Having signed with the Chargers, Hadl flourished under their head coach, Sid Gillman, who devised brilliant passing schemes.

“The league took the philosophy that we were going to have an offensive show,” Hadl recalled in a 2006 interview with The Orlando Sentinel. “We were going to score as many points as we could and not emphasize defense so we can have as exciting a game as we could for the fans and for the TVs. That was our calling card.”

Hadl’s favorite target was the future Hall of Fame wide receiver Lance Alworth, known as Bambi for his graceful moves to elude defensive backs.

“I think John is in the top three or five who have played the game,” Alworth told The Union-Tribune. “No. 1, he was a winner, and that to me is what you judge people by when you look at their records.”

The Chargers’ offense also featured the outstanding running backs Paul Lowe and Keith Lincoln and a formidable offensive line led by tackle Ron Mix, another Hall of Famer of the future.

Hadl, who played for the Chargers from 1962 to 1972, appeared in three A.F.L. championship games, a 51-10 trouncing of the Boston Patriots (now the New England Patriots) and two losses to the Buffalo Bills.

Following the 1972 season, the Chargers traded Hadl to the Rams, who had dealt quarterback Roman Gabriel to the Philadelphia Eagles. The Rams were 6-7-1 in 1972, but under their new head coach, Chuck Knox, and buoyed by Hadl’s passing, they improved to 12-2.

Hadl, at age 33, threw four touchdown passes to Harold Jackson in the Rams’ 37-31 victory over Dallas during the 1973 regular season and completed 135 of 258 passes for 2,008 yards and 22 touchdowns. The Rams lost to the Cowboys, 27-16, in the first round of the playoffs, but Hadl was the National Football Conference’s player of the year and started at quarterback in the Pro Bowl game against the American Football Conference. (Following the A.F.L.-N.F.L. merger in 1970, the N.F.L. split into two conferences.)

In midseason 1974, the Rams gave the No. 1 quarterback spot to James Harris, a fourth-year player who had been Hadl’s backup the previous year, and traded Hadl to the Green Bay Packers for five high-round draft picks. Hadl played for the Packers through the 1975 season, then concluded his career with the Houston Oilers in 1976 and 1977.

He was the A.F.L. or N.F.L. season leader in passing yardage three times and the leader in passes completed and touchdown passes twice.

Hadl passed for 244 touchdowns and 33,503 yards in his 11 years with the Chargers and five years with the Rams, Packers and Oilers.

John Willard Hadl was born on Feb. 15, 1940, in Lawrence, Kan., the home of the University of Kansas, a son of Jess and Judy Hadl. His father was a mechanic.

John was an all-state halfback at Lawrence High School. In his three seasons with Kansas, he ran for 1,041 yards and passed for 1,345 yards. He led the nation in punting as a sophomore with an average of 45.6 yards.

After retiring as a player, Hadl was an assistant coach with the Rams and John Elway’s first quarterback coach, with the 1983 Denver Broncos. He was also head coach of the Los Angeles Express in the United States Football League of the 1980s.

Hadl was an offensive coordinator for the Kansas football team as well and later spent 30 years with the university’s athletic department, mainly in fund-raising, before retiring in 2018.

For all his success running the Chargers’ passing attack, Hadl was overshadowed at times by the highly popular Alworth.

But Alworth felt that the perception was unfair. “He had a lot of touch with his throws, and he threw a great long ball, which was great for me,” he said. “I don’t really believe that he got the credit he was due.”