Gus Niarhos, who died Wednesday in Harrisonburg, Va., at age 84, served as backup catcher for the Yankees during some of Yogi Berra’s best years.

Niarhos played nine seasons with four different major league clubs, and, presumably because he was always more of a benchwarmer than an everyday player, he had time to contemplate the design of the traditional catcher’s mitt. He is credited with introducing a key innovation: the hinged palm.

Traditional catcher’s mitts were pillow like, with plenty of padding on the palm to cushion the impact of the pitch. It was not easy to actually grasp a baseball in the mitt, and catching was a two-handed operation – the mitt stopped the ball, which then fell down into a bare hand.

“Sometimes during the latter half of his career, Gus was fooling around with his mitt, and cut a hole or two down the middle of the palm area, thus making it possible to snap the glove shut like a trap, or a hinge,” Tom Wiles, director of research at the Baseball Hall of Fame, wrote in his online newsletter, “Letters in the Dirt.”

According to Wiles, Niarhos’s innovation made it possible for catchers to keep their bare hand behind their bodies, where it would be protected from injury. Johnny Bench of the Cincinnati Reds is generally credited with being the first catcher to regularly use this technique. Hinged mitts made possible stabbing catches, enabling the catcher to control wild pitches more easily.

Constantine Gregory Niarhos was born in Birmingham, Ala., and was a three-sport athlete in high school. He was signed by the Yankees while attending Auburn University on a baseball scholarship. He served in the Navy during World War II and made his major league debut on June 9, 1946.