New York Mets catcher John Stearns at spring training camp in...

New York Mets catcher John Stearns at spring training camp in St. Petersburg, Fla., in March 1977.  Credit: AP/Harry Harris

John Stearns didn’t back away from a fight when he thought it was worth fighting.

He didn’t do it as a college football safety, and he certainly didn’t do it as the Mets’ catcher in 1980, when he tackled two fans who had scrambled onto the field. He once even charged the mound .  .  . from the dugout.

And maybe that’s expected when you had the size and the swagger that Stearns did: 6 feet tall and broad, and the nickname “Bad Dude.”

He was one of the best catchers in Mets history, playing during the late 1970s and early ’80s, an era that didn’t boast a lot of franchise bests.

Stearns’ resolve was on display three weeks ago when he emerged from the dugout on Old-Timers’ Day at Citi Field despite breaking his hip in April and being in the late stages of prostate cancer. He walked proudly onto the field with his son close by and was able to soak in the cheers from an adoring crowd one last time.

Stearns died late Thursday after a long battle with the disease, the team announced. He was 71.

“No one played the game with more spirit or determination than John Stearns,” team president Sandy Alderson said in a statement. “He literally willed himself to attend Old-Timers’ Day last month so he could visit friends and old teammates. Despite his illness, he even managed to step into the batting cage to take a few swings. His nickname, ‘Bad Dude,’ couldn’t have been more appropriate. A four-time All-Star, John was one of the most complete catchers in Mets history. Our thoughts and prayers are with his friends and family.”

A two-sport athlete out of the University of Colorado, Stearns was drafted by the Bills and Phillies in 1973 before opting to pursue baseball. He spent two seasons with the Phillies’ organization, rising to the big-league club for one game in 1974, then was traded to the Mets — in a package that sent Tug McGraw to Philadelphia — and spent the rest of his major-league playing career with them.

Stearns was a four-time All-Star with remarkable speed for a catcher (his 25 stolen bases in 1978 set the National League record at the position) and a lifetime .260 batting average.

His career was cut short in 1984 due to injury, but Stearns stayed in baseball as a broadcaster and coach. He was the bench coach for the 2000 Mets and was mic’d up when Mike Piazza hit a home run in Game 1 of the NLCS, famously bellowing, “The monster is out of the cage!” That became the team’s motto, one that took them all the way to the World Series.

“John was such a key part of our staff,” said Bobby Valentine, the manager then. “He had a unique way of lighting a fire under the guys. Every time we spoke by phone, he kept telling me he was going to beat this thing. That was John Stearns to a T.’’

Right until the end, Stearns fought the disease, telling the Denver Post in July that he had no intention of letting up. He mentioned then, too, that he still was getting 20-odd letters from fans a day, a testament to what he meant to the franchise.

While others wondered if he’d be well enough to make the trip from his home in Colorado to Flushing for Old-Timers’ Day on Aug. 27, the “Bad Dude” lived up to his nickname. He made it, put on his uniform, and stepped into the cage.

“I am heartbroken,” said Lee Mazzilli, his teammate for six seasons. “John was just a joy to be around. He loved the game so much. I was amazed when he went to the batting cage on Old-Timers’ Day. That just showed you how much of a competitor he was.”

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