Stanley J. Kopec Jr. died of brain cancer at his home in Pepperell at the age of 63 last week. He taught math, worked in high tech for three decades, and loved to play golf. By all accounts, he lived a quiet and happy life in Central Massachusetts. He leaves his wife, his sister, and extended family members. His obituary read, “As genuine as they come, there was not a bone of pretense in his body.’’

I know that’s true. Fifty years ago, Stan was my baseball teammate. We always called him “Woody.’’

I lost touch with Woody a long time ago. We connected a few times at reunions and funerals — and occasionally he’d send me an e-mail about something in the world of sports — but life and choices simply sent us in different directions.

When a friend sent me a text notifying me of Woody’s passing, I got to thinking about the bonds we form as teammates.

Woody played third base for the Groton Little League Braves in the mid-1960s. A chunky 10-year-old, he batted right, threw right, wore dark-rimmed glasses, and could really hit. I think he led the league in homers in his final year of Little League. We remained teammates through Babe Ruth summers and a couple of high school seasons. As a teenager, he was quiet, steady, and really good with the glove. We all knew he was better at math than the rest of us, but he wasn’t one to brag about anything. He didn’t slam his helmet when he struck out. He didn’t call attention to himself. Just like the obit said, “there was not a bone of pretense.’’

If you play team sports, you have dozens, maybe hundreds of folks like this in your life. Through the random elements of geography, age, and skill level, you are thrown together with people who share the same goals as yourself. They become your daily sports family. Just like with real family, you don’t get to choose who they are. And just like with real family, they can make you feel great, or they can make you miserable.

Boxers, golfers, gymnasts, skaters, and tennis players don’t have the same experience. They’re out there by themselves. They alone control their success or failure. There is nobody with whom to share glory. Likewise, there is no one to blame. It’s all on you. We all know some team players who would have been better off in individual sports.

If you play team sports, you spend more time with your teammates than just about anyone else. You share things with them that no one else knows. You have your own language. You have inside jokes. A word to a teammate triggers a memory and a laugh. And only you and your teammates know what you are laughing about.

These bonds are forged through the sheer volume of time you spend with one another and the ways you learn to cope. A shortstop and second baseman develop their own signal system to tell one another who’s covering second on the next pitch. Two guys who never get to play bond on the bench, sitting side by side, telling jokes and no doubt agreeing that they are getting screwed over by the coach. They are teammates.

Some teammates don’t like each other. It’s inevitable. Teammates do not ask to be put together, but the success of the team usually requires that they learn to live and work with one another. It’s a life lesson. You learn that you don’t have to like the other guy, but you’re going to have to figure out how to work with him. Go back and listen to Denzel Washington’s speech in “Remember the Titans,’’ when coach Herman Boone has his team visit the Gettysburg battleground and tells them, “I don’t care if you like each other or not, but you will respect each other.’’

This dynamic never changes, not even at the highest levels of professional team sports. Pedro Martinez and Curt Schilling didn’t particularly like one another, but for one season they put their personal stuff on the shelf and worked together to deliver a World Series championship to Boston.

When Larry Bird told us that Dennis Johnson was the best teammate he ever played with, Larry was not pretending that DJ was a better player or in any way a better guy than Kevin McHale. He was simply paying DJ the highest compliment he could deliver. Larry was telling us that DJ would do anything it took to win. DJ did not need to feed his ego. He did not need “touches.’’ He would take the charge. He would wear himself out guarding Magic Johnson. And when Larry stole the ball on the inbounds pass against the Pistons, DJ would know that his job was to immediately cut to the basket.

The top of Mickey Mantle’s plaque in Yankee Stadium’s Monument Park says nothing about Mantle’s seven championship rings, three MVP awards, or 536 homers. It reads:

Mickey Mantle

“A Great Teammate’’

A teammate is someone with whom you shared . . . hits, runs, errors, and maybe coffee frappes after the games. Wins and losses. You had a common goal. You went through changes together. You grew up and probably grew apart. But wherever you go and whatever you do, your former teammates are part of your history. There was a time when the thing you were doing together felt like the thing that mattered most.

RIP, Stanley Kopec.

Dan Shaughnessy is a Globe columnist. He can be reached at dshaughnessy@globe.com. Follow him on Twitter @dan_shaughnessy.