For example, early in his career, Posey’s hands were so quick he would try blocking pitches by just snatching them with his glove. Hayes showed him how to lead with his hands but to get his body down as well. He was always demonstrating.

“He’s easy to talk to and has a good feel,” Posey said. “He’s somebody to bounce stuff off of. If I ever need anything extra, he’s always there. He’s been huge for me.”

Once, Hayes was a first-round draft selection himself, selected by the Chicago Cubs with the 13th pick in 1978 after he caught their attention with his play at Indiana State. He went one pick after Kirk Gibson was taken by the Detroit Tigers.

But unlike Gibson, or Posey, Hayes’s major league career lasted all of nine at-bats, over two seasons. He spent a few more years in the minors, shifted to coaching and then spent 14 years as a minor league manager.

He served as the bullpen coach for the Colorado Rockies for one season, but his first extended shot at the majors came in 2003, when the Giants gave him the job he still holds. By then, he was 45, but in many ways, the best part of his baseball career had just begun.

During games, Hayes sits with the relievers in the bullpen and catches for them when the call comes from the dugout to get ready. He passes the time — and there is often a lot of time to kill in the bullpen — telling baseball stories or hunting stories, or just sharing jokes. He has the ease that comes with so much baseball experience, that lets him ad-lib when he feels the urge. Once, when the left-handed reliever Jeremy Affeldt was warming up, Hayes turned to a fan sitting nearby and said, “Would you put him in if he’s throwing like that?”

When he’s not joking, and often enough he’s not, Hayes offers relievers the insights he inevitably gathers as he catches them in the bullpen. He knows that the pressure increases on the relievers as the postseason arrives and that it is his job to calm them down and help them focus, or maybe just leave them alone.